Podcast
Questions and Answers
What causes the top string to break when it is pulled down slowly?
What causes the top string to break when it is pulled down slowly?
- The weight of the ball. (correct)
- The density of the ball.
- The volume of the ball.
- The mass of the ball.
According to Newton's 2nd Law, how is acceleration related to net force and mass?
According to Newton's 2nd Law, how is acceleration related to net force and mass?
- Acceleration is directly proportional to net force and inversely proportional to mass. (correct)
- Acceleration is inversely proportional to net force.
- Acceleration does not depend on mass.
- Acceleration is directly proportional to mass.
If both the net force and the mass of an object are doubled, what happens to the acceleration?
If both the net force and the mass of an object are doubled, what happens to the acceleration?
- Acceleration increases by a factor of four.
- Acceleration doubles.
- Acceleration remains unchanged. (correct)
- Acceleration is halved.
What occurs to acceleration if the net force acting on an object is quadrupled while the mass remains constant?
What occurs to acceleration if the net force acting on an object is quadrupled while the mass remains constant?
If a car can accelerate at $2 ext{ m/s}^2$, what is the acceleration when towing another car of equal mass?
If a car can accelerate at $2 ext{ m/s}^2$, what is the acceleration when towing another car of equal mass?
How does increasing an object's mass affect its acceleration when a constant net force is applied?
How does increasing an object's mass affect its acceleration when a constant net force is applied?
Under which condition would an object's acceleration be most affected?
Under which condition would an object's acceleration be most affected?
What relationship does Newton's 2nd Law establish between force, mass, and acceleration?
What relationship does Newton's 2nd Law establish between force, mass, and acceleration?
What does the term 'normal' refer to in the context of forces?
What does the term 'normal' refer to in the context of forces?
If a person evenly distributes their weight across two bathroom scales, what will each scale read?
If a person evenly distributes their weight across two bathroom scales, what will each scale read?
In the context of a gymnast hanging from two rings, how do the scale readings compare to her total weight when evenly distributed?
In the context of a gymnast hanging from two rings, how do the scale readings compare to her total weight when evenly distributed?
In static equilibrium, what is the relationship between the sum of forces and motion?
In static equilibrium, what is the relationship between the sum of forces and motion?
If a gymnast supports more weight on one ring than the other, how will the scale on the ring with less weight behave?
If a gymnast supports more weight on one ring than the other, how will the scale on the ring with less weight behave?
What type of motion is characterized by constant speed in a straight line?
What type of motion is characterized by constant speed in a straight line?
What can be inferred about the forces acting on an object in equilibrium?
What can be inferred about the forces acting on an object in equilibrium?
Which statement correctly describes a situation when two scales measure the weight of an object?
Which statement correctly describes a situation when two scales measure the weight of an object?
What does Newton's 3rd Law state about forces in interactions?
What does Newton's 3rd Law state about forces in interactions?
Why does Earth not 'jump up' when a boulder exerts a force on it?
Why does Earth not 'jump up' when a boulder exerts a force on it?
What is the relationship between mass and acceleration as per Newton's 3rd Law?
What is the relationship between mass and acceleration as per Newton's 3rd Law?
In a scenario where a cannon fires a cannonball, why does the cannonball accelerate more than the cannon?
In a scenario where a cannon fires a cannonball, why does the cannonball accelerate more than the cannon?
What occurs when a balloon is released and the trapped air escapes?
What occurs when a balloon is released and the trapped air escapes?
When swimming, how do the forces between a swimmer and water operate?
When swimming, how do the forces between a swimmer and water operate?
How does the interaction between the tires of a car and the road contribute to motion?
How does the interaction between the tires of a car and the road contribute to motion?
What primarily determines the acceleration experienced by an object when subjected to force?
What primarily determines the acceleration experienced by an object when subjected to force?
What is necessary for a system to accelerate?
What is necessary for a system to accelerate?
In the context of the horse-cart system, what role do the forces exerted by the horse on the cart and the cart on the horse play?
In the context of the horse-cart system, what role do the forces exerted by the horse on the cart and the cart on the horse play?
What forces interact to provide acceleration for the horse-cart system as a whole?
What forces interact to provide acceleration for the horse-cart system as a whole?
What happens when the apple pushes against the floor?
What happens when the apple pushes against the floor?
In a situation involving interatomic forces within a baseball, how do these forces affect the ball's acceleration?
In a situation involving interatomic forces within a baseball, how do these forces affect the ball's acceleration?
Why does the farmer focus on the net force exerted on the cart system?
Why does the farmer focus on the net force exerted on the cart system?
What is the role of the ground in the horse's movement?
What is the role of the ground in the horse's movement?
What contributes to the acceleration of the entire horse-cart system?
What contributes to the acceleration of the entire horse-cart system?
What is the equation for the net force acting on the cart?
What is the equation for the net force acting on the cart?
According to Newton’s laws, what happens if the net force on an object is not zero?
According to Newton’s laws, what happens if the net force on an object is not zero?
What is the primary direction of Nellie Newton's force when pulling the sled?
What is the primary direction of Nellie Newton's force when pulling the sled?
What are the two other forces acting on the sled, apart from Nellie's force?
What are the two other forces acting on the sled, apart from Nellie's force?
Which of the following statements accurately represents Newton’s Third Law of Motion?
Which of the following statements accurately represents Newton’s Third Law of Motion?
In a free-body diagram (FBD) for an object, what does each vector represent?
In a free-body diagram (FBD) for an object, what does each vector represent?
What happens to the vertical component of a vector when an object is projected at an angle?
What happens to the vertical component of a vector when an object is projected at an angle?
If an object is not accelerating, what can be inferred about the net force acting on it?
If an object is not accelerating, what can be inferred about the net force acting on it?
What is escape speed necessary for an object to leave the gravitational influence of Earth?
What is escape speed necessary for an object to leave the gravitational influence of Earth?
What happens to an object that achieves escape velocity from Earth?
What happens to an object that achieves escape velocity from Earth?
What is the escape speed required to leave the solar system from Earth's distance from the Sun?
What is the escape speed required to leave the solar system from Earth's distance from the Sun?
If an object reaches the escape speed, it primarily alters its trajectory from which of the following types of orbits?
If an object reaches the escape speed, it primarily alters its trajectory from which of the following types of orbits?
Which statement about escape velocity is incorrect?
Which statement about escape velocity is incorrect?
How does an increase in rotational speed affect tangential speed?
How does an increase in rotational speed affect tangential speed?
What is the relationship between the radius from the axis and linear speed?
What is the relationship between the radius from the axis and linear speed?
What direction does centripetal acceleration point?
What direction does centripetal acceleration point?
What essential condition allows a car to remain on a curved path while driving?
What essential condition allows a car to remain on a curved path while driving?
What happens to water in a washing machine during the spinning cycle?
What happens to water in a washing machine during the spinning cycle?
Centripetal force is dependent on which of the following factors?
Centripetal force is dependent on which of the following factors?
If a friend sits halfway to the center of a rotating disk, what is her rotational speed compared to yours, sitting at the edge?
If a friend sits halfway to the center of a rotating disk, what is her rotational speed compared to yours, sitting at the edge?
What occurs if the force of friction is insufficient for a car navigating a curve?
What occurs if the force of friction is insufficient for a car navigating a curve?
What two factors determine centripetal acceleration?
What two factors determine centripetal acceleration?
What provides the centripetal acceleration for a car rounding a banked curve?
What provides the centripetal acceleration for a car rounding a banked curve?
What does the term 'centrifugal force' refer to in circular motion?
What does the term 'centrifugal force' refer to in circular motion?
When analyzing a conical pendulum, what is the y-direction force equation associated with the bob's weight?
When analyzing a conical pendulum, what is the y-direction force equation associated with the bob's weight?
In the context of a conical pendulum, which component of tension provides the centripetal acceleration?
In the context of a conical pendulum, which component of tension provides the centripetal acceleration?
What must happen for an object in circular motion once the centripetal force is removed?
What must happen for an object in circular motion once the centripetal force is removed?
What does the tension in the string of a conical pendulum represent when resolved into components?
What does the tension in the string of a conical pendulum represent when resolved into components?
In a conical pendulum, when the bob is not moving vertically, what can be inferred about the net force in the y-direction?
In a conical pendulum, when the bob is not moving vertically, what can be inferred about the net force in the y-direction?
What is the period of a geosynchronous satellite at about 6.5 Earth radii?
What is the period of a geosynchronous satellite at about 6.5 Earth radii?
What shape do orbits generally take around a planet?
What shape do orbits generally take around a planet?
How does the altitude of a satellite affect its orbital period?
How does the altitude of a satellite affect its orbital period?
What is the expected vertical distance a horizontally thrown rock will fall after one second?
What is the expected vertical distance a horizontally thrown rock will fall after one second?
What factor is primarily responsible for a satellite's speed at different positions in its orbit?
What factor is primarily responsible for a satellite's speed at different positions in its orbit?
What period does the International Space Station (ISS) complete an orbit in?
What period does the International Space Station (ISS) complete an orbit in?
For a projectile with high speed, where is the center of Earth likely located in an elliptical orbit?
For a projectile with high speed, where is the center of Earth likely located in an elliptical orbit?
In a satellite's orbit, which position will it have the least speed?
In a satellite's orbit, which position will it have the least speed?
What is the result of doubling both masses and tripling the distance between them in terms of gravitational force?
What is the result of doubling both masses and tripling the distance between them in terms of gravitational force?
What is the gravitational field strength at the surface of Earth as per the provided formula?
What is the gravitational field strength at the surface of Earth as per the provided formula?
How does the presence of mass affect the gravitational field created in space?
How does the presence of mass affect the gravitational field created in space?
What analogy is used to explain the effect of gravitational fields on space-time?
What analogy is used to explain the effect of gravitational fields on space-time?
What defines the variations in ocean levels referred to as tides?
What defines the variations in ocean levels referred to as tides?
If the radius of Earth is approximately $6.4 imes 10^6 m$, which of the following calculations would be used to determine the gravitational force at its surface?
If the radius of Earth is approximately $6.4 imes 10^6 m$, which of the following calculations would be used to determine the gravitational force at its surface?
What impact does the distance between two masses have on gravitational force?
What impact does the distance between two masses have on gravitational force?
What physical principle underpins the explanation of gravitational fields as alterations of space?
What physical principle underpins the explanation of gravitational fields as alterations of space?
Why is it preferable for a car to hit a haystack rather than a concrete wall when it is out of control?
Why is it preferable for a car to hit a haystack rather than a concrete wall when it is out of control?
How does increasing the contact time of a punch reduce the resulting force?
How does increasing the contact time of a punch reduce the resulting force?
What must happen for an object to bounce?
What must happen for an object to bounce?
What is required for the momentum of a system to change?
What is required for the momentum of a system to change?
What is the net momentum of the cannon-cannonball system before firing?
What is the net momentum of the cannon-cannonball system before firing?
How does the design of Lester A. Pelton's paddle improve the efficiency of a waterwheel?
How does the design of Lester A. Pelton's paddle improve the efficiency of a waterwheel?
What happens to the net momentum of a system if no external forces are applied?
What happens to the net momentum of a system if no external forces are applied?
If the impulse delivered to a bouncing object is twice that of an object stopped at rest, what can be said about the bouncing object?
If the impulse delivered to a bouncing object is twice that of an object stopped at rest, what can be said about the bouncing object?
What does the conservation of momentum state about two colliding objects in the absence of external forces?
What does the conservation of momentum state about two colliding objects in the absence of external forces?
In an elastic collision, what additional condition must be met besides momentum being conserved?
In an elastic collision, what additional condition must be met besides momentum being conserved?
Which type of collision occurs when two objects couple together after the impact?
Which type of collision occurs when two objects couple together after the impact?
If a freight car A moving towards a stationary freight car B collides and they couple together, what happens to the speed of the coupled cars compared to the initial speed of freight car A?
If a freight car A moving towards a stationary freight car B collides and they couple together, what happens to the speed of the coupled cars compared to the initial speed of freight car A?
In an inelastic collision, what typically happens to the total kinetic energy of the system?
In an inelastic collision, what typically happens to the total kinetic energy of the system?
Which statement correctly reflects Newton's second law concerning momentum?
Which statement correctly reflects Newton's second law concerning momentum?
What defines an elastic collision compared to an inelastic collision?
What defines an elastic collision compared to an inelastic collision?
When two identical freight cars collide inelastically and couple together, what can be said about their momentum?
When two identical freight cars collide inelastically and couple together, what can be said about their momentum?
What is the unit of measurement for work, which combines a unit of force and a unit of distance?
What is the unit of measurement for work, which combines a unit of force and a unit of distance?
When a force is exerted but there is no displacement of the object, what can be concluded about the work done?
When a force is exerted but there is no displacement of the object, what can be concluded about the work done?
If you push a cart with a constant force and then push it twice as far, how much work have you done?
If you push a cart with a constant force and then push it twice as far, how much work have you done?
What aspect of energy quantifies a system's ability to do work?
What aspect of energy quantifies a system's ability to do work?
Which of the following scenarios does not involve work being done?
Which of the following scenarios does not involve work being done?
What is the result of doubling the load lifted a certain height compared to lifting a single load the same height?
What is the result of doubling the load lifted a certain height compared to lifting a single load the same height?
What is the correct equation to calculate work done when a force is applied over a distance?
What is the correct equation to calculate work done when a force is applied over a distance?
Which of the following statements correctly describes energy in a system?
Which of the following statements correctly describes energy in a system?
What must occur to increase the kinetic energy of an object?
What must occur to increase the kinetic energy of an object?
In the presence of friction, which factor affects the net work done on a moving object?
In the presence of friction, which factor affects the net work done on a moving object?
If an object’s kinetic energy remains unchanged while work is being done, what can be concluded?
If an object’s kinetic energy remains unchanged while work is being done, what can be concluded?
What does the term 'net work' refer to in a system with friction?
What does the term 'net work' refer to in a system with friction?
What impact does friction have when a crate slides and comes to a stop?
What impact does friction have when a crate slides and comes to a stop?
If a cart is moving and 100 J of work is done on it, under which condition would it not gain 100 J of kinetic energy?
If a cart is moving and 100 J of work is done on it, under which condition would it not gain 100 J of kinetic energy?
What would indicate that no work is being done on an object that is being pushed?
What would indicate that no work is being done on an object that is being pushed?
How is the work done to stop a car determined?
How is the work done to stop a car determined?
What is the primary function of a lever in simple machines?
What is the primary function of a lever in simple machines?
How many classes of levers are identified based on the positions of the effort, load, and fulcrum?
How many classes of levers are identified based on the positions of the effort, load, and fulcrum?
What does a pulley achieve when it operates?
What does a pulley achieve when it operates?
What principle do all simple machines operate under?
What principle do all simple machines operate under?
In terms of mechanical advantage, how can the input force be adjusted?
In terms of mechanical advantage, how can the input force be adjusted?
What is the role of the fulcrum in a lever?
What is the role of the fulcrum in a lever?
What does the equation $F d = F d$ signify in the context of levers?
What does the equation $F d = F d$ signify in the context of levers?
What happens to the output force when using a system of pulleys?
What happens to the output force when using a system of pulleys?
What happens to a ball's kinetic energy when it bounces?
What happens to a ball's kinetic energy when it bounces?
The principle of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another.
The principle of conservation of energy states that energy cannot be created or destroyed, only converted from one form to another.
What is the formula to calculate gravitational potential energy?
What is the formula to calculate gravitational potential energy?
During free fall, a falling object's momentum increases due to its increasing ________.
During free fall, a falling object's momentum increases due to its increasing ________.
Match the energy types with their definitions:
Match the energy types with their definitions:
Which car experiences greater acceleration when equal forces are applied?
Which car experiences greater acceleration when equal forces are applied?
When the force is removed from the cars after accelerating, the compact car will have greater momentum than the full-size sedan.
When the force is removed from the cars after accelerating, the compact car will have greater momentum than the full-size sedan.
What effect does gravitational potential energy (PE) experience during the free fall of Bronco?
What effect does gravitational potential energy (PE) experience during the free fall of Bronco?
The relationship between work done and kinetic energy is expressed as W = _____ KE.
The relationship between work done and kinetic energy is expressed as W = _____ KE.
Match the following terms with their definitions:
Match the following terms with their definitions:
Which force impacts the motion of the cars as they accelerate?
Which force impacts the motion of the cars as they accelerate?
The amount of work done on both cars is the same if they travel equal distances under equal forces.
The amount of work done on both cars is the same if they travel equal distances under equal forces.
What two types of potential energy are changing during Bronco's slowing-down interval?
What two types of potential energy are changing during Bronco's slowing-down interval?
How much work is needed to lift a 200 N object to a height of 4 meters?
How much work is needed to lift a 200 N object to a height of 4 meters?
The potential energy of an object increases as it is lifted higher above the ground.
The potential energy of an object increases as it is lifted higher above the ground.
What is the formula for calculating power?
What is the formula for calculating power?
The potential energy of a mass can be found using the formula PE = ______ x height.
The potential energy of a mass can be found using the formula PE = ______ x height.
Match each scenario with its corresponding energy concept:
Match each scenario with its corresponding energy concept:
What is the power output of an engine that does 60,000 J of work in 10 seconds?
What is the power output of an engine that does 60,000 J of work in 10 seconds?
If an object is sliding down a ramp with friction, it will have more kinetic energy at the bottom than without friction.
If an object is sliding down a ramp with friction, it will have more kinetic energy at the bottom than without friction.
What happens to the speed of an object as it falls freely under gravity?
What happens to the speed of an object as it falls freely under gravity?
What is the resultant vector when two vectors are added at an angle using the parallelogram rule?
What is the resultant vector when two vectors are added at an angle using the parallelogram rule?
The horizontal component of a force acting on an object is always equal to the net force acting on that object.
The horizontal component of a force acting on an object is always equal to the net force acting on that object.
What does the normal force represent in the context of an object resting on an inclined plane?
What does the normal force represent in the context of an object resting on an inclined plane?
The component of weight parallel to the inclined plane is greater than the ______ when the plane is inclined.
The component of weight parallel to the inclined plane is greater than the ______ when the plane is inclined.
Match each force acting on a block on an inclined plane to its function:
Match each force acting on a block on an inclined plane to its function:
Which component of vector T at point B should be equal to W/2 for equilibrium?
Which component of vector T at point B should be equal to W/2 for equilibrium?
In a free-body diagram, each vector represents a force acting on the object.
In a free-body diagram, each vector represents a force acting on the object.
How does the horizontal component of the tension at B relate to the horizontal components at hinge A?
How does the horizontal component of the tension at B relate to the horizontal components at hinge A?
Which component of velocity remains constant while an object is in free motion along a horizontal path?
Which component of velocity remains constant while an object is in free motion along a horizontal path?
The vertical component of velocity decreases as the object travels upwards.
The vertical component of velocity decreases as the object travels upwards.
What effect does a force have on the velocity of an object according to Newton's Third Law?
What effect does a force have on the velocity of an object according to Newton's Third Law?
The __________ rule is used to find the resultant vector of two or more vectors acting at a point.
The __________ rule is used to find the resultant vector of two or more vectors acting at a point.
What happens to the resultant vector when two forces of equal magnitude act at angles of 90 degrees?
What happens to the resultant vector when two forces of equal magnitude act at angles of 90 degrees?
Match the following forces with their corresponding effects on an object:
Match the following forces with their corresponding effects on an object:
At what moment does the vertical component of velocity equal zero during an object's projectile motion?
At what moment does the vertical component of velocity equal zero during an object's projectile motion?
Velocity vectors combine with force vectors when determining an object's motion.
Velocity vectors combine with force vectors when determining an object's motion.
In the context of a sailboat affected by wind, which component of force helps it to move forward?
In the context of a sailboat affected by wind, which component of force helps it to move forward?
The tension in a rope must be equal to the weight of the object it is supporting.
The tension in a rope must be equal to the weight of the object it is supporting.
What relationship do you see between the vectors formed by the tensions in ropes A, B, and C when a lantern is suspended?
What relationship do you see between the vectors formed by the tensions in ropes A, B, and C when a lantern is suspended?
When analyzing vector components, the _____ component causes acceleration in the direction of motion.
When analyzing vector components, the _____ component causes acceleration in the direction of motion.
Which statement is true regarding the impact of wind on sailboats?
Which statement is true regarding the impact of wind on sailboats?
Match the following terms with their correct definitions:
Match the following terms with their correct definitions:
What happens to a boat's movement if the pulling force on the rope becomes perpendicular to the track?
What happens to a boat's movement if the pulling force on the rope becomes perpendicular to the track?
A component of force that acts perpendicular to an object's path always causes motion.
A component of force that acts perpendicular to an object's path always causes motion.
Study Notes
Tension in a String
- The tension in the top string of a hanging object is equal to the tension in the bottom string plus the weight of the object.
- The tension in the top string is greater than the tension in the bottom string, therefore it will break first.
- The tension in a string is a measure of the pulling force applied to the string.
Newton’s Second Law of Motion
- Newton's Second Law of Motion relates the net force acting on an object to its mass and acceleration.
- The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
- If the net force acting on an object doubles, its acceleration doubles.
- If the mass of an object doubles, its acceleration is halved.
- If both the net force and the mass of an object double, its acceleration remains unchanged.
Normal (Support) Forces
- In physics, the word "normal" means "perpendicular".
- The normal force of a surface on an object is the force the surface exerts perpendicular to that surface.
Static and Dynamic Equilibrium
- Static equilibrium occurs when an object is at rest and the net force acting on it is zero, meaning there is no motion.
- Dynamic Equilibrium occurs when an object is moving at a constant speed in a straight line, meaning the net force acting on it is also zero.
Newton’s Third Law
- Newton’s Third Law states that for every force (action) there is an equal and opposite force (reaction).
- The forces always occur in pairs, and act on different objects in the interaction.
- The forces are equal in magnitude but opposite in direction.
- The magnitudes of the forces are always equal, however, the accelerations caused by the forces can be different due to different masses of the objects involved.
Action-Reaction Pairs
- When object 'A' exerts a force on object 'B', object 'B' exerts an equal and opposite force on object 'A'.
- While the forces are equal in magnitude, the accelerations produced depend on the masses of the objects.
- Internal forces within a system, such as the forces between parts of a single object, cancel out and do not contribute to the acceleration of the system.
- An external force is necessary to accelerate a system as a whole.
Horse-Cart Problem
- The horse-cart system is a classic example of action-reaction pairs.
- The horse pulls the cart forward and the cart pulls the horse backwards, these forces are equal in magnitude and opposite in direction, but they are internal forces within the system.
- The horse-cart system needs an external force, such as friction between the horse's feet and the ground, to move forward.
Vector Components
- Vectors are quantities that have both magnitude and direction.
- Vector components are the projections of a vector onto the x-axis (horizontal) and the y-axis (vertical).
- When analyzing motion in two dimensions, it's often helpful to break forces down into their horizontal and vertical components.
Summary of Forces
- Newton’s laws of motion are fundamental principles of physics, which explain how forces interact with and affect objects.
- The steps to solve force problems include drawing a free body diagram for each object of interest, labelling all forces with their directions, and applying Newton’s laws to determine the net force and acceleration of each object.
Centripetal Acceleration and Force
- Centripetal acceleration is the acceleration that causes an object to move in a circular path.
- The magnitude of centripetal acceleration is directly proportional to the square of the object's speed and inversely proportional to the radius of the circular path.
- Centripetal force is the force that causes centripetal acceleration.
- Centripetal force is always directed towards the center of the circular path.
Conical Pendulum
- A conical pendulum consists of a bob swinging in a circular path, with the string tracing a cone.
- Tension in the string and gravitational force act on the bob.
- The horizontal component of the tension provides the centripetal force, while the vertical component balances the weight of the bob.
Banked Curves
- The horizontal component of the normal force acting on a car rounding a banked curve provides the centripetal force.
- Friction also contributes to the centripetal force.
Centrifugal Force
- There is no actual force called "centrifugal force".
- The apparent outward force experienced by a person or object in circular motion is actually due to inertia.
Rotational Speed
- Rotational speed is the rate at which an object rotates.
- It is measured in revolutions per minute (RPM).
- Tangential speed is the linear speed of an object in circular motion.
- Tangential speed is directly proportional to the rotational speed and the radius of the circular path.
Gravitational Force
- The force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
Gravitational Field
- A gravitational field is an alteration of space around a massive object.
- It is a vector field, representing the force that would be experienced by a test mass at each point in space.
- The strength of the gravitational field is directly proportional to the mass of the object and inversely proportional to the square of the distance from the object.
Ocean Tides
- Tides are the periodic rise and fall of ocean water levels.
- They are caused by the gravitational pull of the Moon and the Sun.
- There are typically two high tides and two low tides each day.
Satellite Motion
- Satellites orbit Earth due to a balance between their inertia and Earth's gravity.
- The period of a satellite's orbit depends on its altitude.
- The speed of a satellite in its orbit is not constant; it is faster when it is closer to Earth and slower when it is farther away.
Escape Velocity
- Escape velocity is the minimum speed an object needs to escape the gravitational pull of a planet or star.
- It is the speed at which the object's kinetic energy is greater than or equal to its gravitational potential energy.
- For Earth, the escape velocity is approximately 11 km/s.
- For the Sun, the escape velocity at Earth's distance is about 42 km/s.
Impulse and Momentum
- Impulse occurs when a force acts on an object over time.
- The change in momentum equals the impulse on the object.
- A boxer riding with a punch increases the contact time and reduces the impact force.
- Momentum is conserved when no external forces are acting on a system.
- Collisions can be elastic (conserving kinetic energy) or inelastic (some kinetic energy is lost due to heat or deformation).
- In a completely inelastic collision, two objects collide and become one.
Work and Energy
- Work is done when a force is applied over a distance in the direction of the force.
- The work-energy theorem states that the net work done on an object equals the change in its kinetic energy.
- Work is needed to change the kinetic energy of an object.
- Friction causes a loss of kinetic energy because energy is transferred into heat and the deformation of the object.
Simple Machines
- A lever is a simple machine that rotates on a fulcrum, enabling a small force over a large distance to induce a large force over a small distance.
- A pulley is a simple machine that functions like a lever with equal arms - it changes the direction of the input force and can multiply the force.
- All simple machines operate under the principle of work in = work out.
- By increasing the effort distance, a smaller force is required to do a given amount of work.
Bronco's Bungee Jump
- Bronco’s mass is 100 kg
- Acceleration of free fall is 10 m/s²
- Distance traveled in free fall for 3 seconds is 45 meters (using d = ½ * a * t²)
- Bronco's velocity after 3 seconds of free fall is 30 m/s (using v = a * t)
- Change in momentum during the 3-second free fall is 3000 kg⋅m/s (using Δmv = m * Δv )
- Change in momentum during the 2-second slowing down period is 3000 kg⋅m/s
- Impulse during the 2-second slowing down period is 3000 N⋅s (using Impulse = Ft)
- Average force exerted by the cord during the 2-second slowing down interval is 1500 N (using Ft = Δmv)
- Bronco's kinetic energy after 3 seconds of free fall is 45,000 J (using KE = ½ * m * v²)
- The decrease in gravitational potential energy during the 3 seconds of free fall is 45,000 J (using PE = m * g * h)
- During the slowing down interval, both gravitational potential energy and elastic potential energy are changing
Cars on a Cliff
- The car with less mass will accelerate more quickly (higher acceleration).
- The car with less mass will spend less time along the surface of the lot.
- Since impulse is Ft and the force and time are the same, the impulse will be the same for both cars.
- Since Ft = Δmv and the force and time are the same, the momentum at the edge of the cliff will be the same for both cars.
- The car with less mass will have more work done on it, since W = F*d, and the force is constant but the car with less mass travels a greater distance.
- The car with less mass will have a higher kinetic energy at the edge of the cliff, because the work done, W = ΔKE.
Conservation of Energy
- The total mechanical energy of a system remains constant (conserved) if no work is done on the system by external forces.
- In a closed system, energy can be converted from one form to another, but it can't be created or destroyed
- Mechanical energy is the sum of potential energy and kinetic energy
- Potential energy is stored energy, such as gravitational potential energy (energy stored due to an object's position relative to Earth)
- Kinetic energy is the energy of motion
More on Energy
- There is a trade-off between potential energy and kinetic energy; when one increases, the other decreases.
- Work is defined as the force applied to an object over a certain distance
- The amount of work done is equal to the change in energy of the object.
- Power is the rate at which work is done.
Friction and Energy
- Inelastic collisions are collisions where kinetic energy is not conserved, and some energy is lost as heat, sound, or deformation.
- Friction is a force that opposes motion, and it can cause energy to be dissipated as heat.
- In real-world scenarios, friction will always play a role, and some energy will always be lost, meaning that the bounce will be less high over time.
- The amount of energy lost due to friction is dependent on the coefficient of friction between the surfaces.
Windmills and Energy
- Windmills use wind energy to generate electricity.
- The power generated by windmills does not affect wind speed.
- Windmills capture kinetic energy from the wind, but this doesn't change the overall amount of energy in the system.
- The wind behind a windmill may appear to be slower, but this is due to the wind being diverted by the blades, not due to a decrease in total wind energy.
Resultant Vectors
- Resultant vector C is produced when vectors A and B are at an angle to each other.
- C is the diagonal of a parallelogram with A and B as adjacent sides
- C is a rectangle when A and B are perpendicular to each other.
Velocity Vectors and Components
- Velocity vectors combine with other velocity vectors.
- Velocity vectors do not combine with force vectors.
Force Vectors and the Parallelogram Rule
- The resultant vector of two rope tensions supporting a heavy ball is equal and opposite to the ball's weight.
- The relative lengths of the sides of the parallelogram are proportional to the rope tensions.
- When a lantern is suspended by three ropes, there is a relationship between the vectors: A + B = C, and A + C = B.
Vectors and Sailboats
- The component of force parallel to the direction of the boat's motion propels the boat forward.
- The component of force perpendicular to the direction of the boat's motion is useless for propulsion.
- A boat oriented at an angle into the wind will tack and move in a forward direction.
- The component of force parallel to the keel of a sailboat will determine its forward direction:
- When the component is perpendicular to the keel, the boat will not move forward.
- When the component is parallel to the keel, the boat will move forward.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the concepts of tension in strings, Newton’s Second Law of Motion, and normal forces. It explores the relationships between forces, mass, and acceleration in physics. Test your understanding of these fundamental principles and their applications in various scenarios.
