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Questions and Answers
What is the weight of a 10 kg crate?
What is the weight of a 10 kg crate?
What is the force on a 2 kg ball that is accelerating at $25 m/s^2$?
What is the force on a 2 kg ball that is accelerating at $25 m/s^2$?
Which component of velocity is zero when a projectile is at its highest point?
Which component of velocity is zero when a projectile is at its highest point?
If a car’s speed doubles, how much more work would it take to stop the car?
If a car’s speed doubles, how much more work would it take to stop the car?
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If a dog pulls on its leash with a force of 50 N, the leash pulls on the dog with how much force?
If a dog pulls on its leash with a force of 50 N, the leash pulls on the dog with how much force?
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What provides the centripetal force on a 2000 kg car turning in a circle with a radius of 12 meters at 10 m/s?
What provides the centripetal force on a 2000 kg car turning in a circle with a radius of 12 meters at 10 m/s?
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Which angle of projectile launch provides the greatest distance?
Which angle of projectile launch provides the greatest distance?
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What is the acceleration of a 1000 kg car with a net force of 200 Newtons acting on it?
What is the acceleration of a 1000 kg car with a net force of 200 Newtons acting on it?
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If object A has more inertia than object B, what does this indicate about object A?
If object A has more inertia than object B, what does this indicate about object A?
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What happens to the horizontal and vertical components of a cannonball's velocity when it is fired horizontally off a cliff?
What happens to the horizontal and vertical components of a cannonball's velocity when it is fired horizontally off a cliff?
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Which of these scenarios requires more impulse?
Which of these scenarios requires more impulse?
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What is the tangential speed of a circular disc with a radius of 2 meters spinning at 5 Hz?
What is the tangential speed of a circular disc with a radius of 2 meters spinning at 5 Hz?
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How do two cars that crash into each other and get stuck together compare in velocity after the crash to their velocity before?
How do two cars that crash into each other and get stuck together compare in velocity after the crash to their velocity before?
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If you throw baseballs at the same initial velocity but different angles, which angle provides the most kinetic energy upon hitting the ground?
If you throw baseballs at the same initial velocity but different angles, which angle provides the most kinetic energy upon hitting the ground?
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What is the change in velocity of a projectile as it reaches its highest point?
What is the change in velocity of a projectile as it reaches its highest point?
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What factor determines how to calculate the speed and distance of a free-falling object?
What factor determines how to calculate the speed and distance of a free-falling object?
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What would be the most significant effect on moving objects if friction did not exist?
What would be the most significant effect on moving objects if friction did not exist?
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What is the total velocity of a cannonball fired horizontally if it falls 20 meters and has horizontal velocity of 100 m/s?
What is the total velocity of a cannonball fired horizontally if it falls 20 meters and has horizontal velocity of 100 m/s?
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When a student pushes on a wall, what is the reaction force?
When a student pushes on a wall, what is the reaction force?
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If a wolf runs 20 meters in 4 seconds, what is its speed?
If a wolf runs 20 meters in 4 seconds, what is its speed?
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What is the gravitational pull on a 60 kg person standing on a planet with a mass of $8.0 x 10^{20}$ kg?
What is the gravitational pull on a 60 kg person standing on a planet with a mass of $8.0 x 10^{20}$ kg?
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Which factor would change the projectile's trajectory when considering air resistance?
Which factor would change the projectile's trajectory when considering air resistance?
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What happens to the kinetic energy of an object when it crashes into a wall and bounces off?
What happens to the kinetic energy of an object when it crashes into a wall and bounces off?
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What angle of launch results in the same horizontal distance as another angle?
What angle of launch results in the same horizontal distance as another angle?
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Study Notes
Friction's Absence and Motion
- Without friction, objects would continue moving at a constant velocity indefinitely, requiring no force to maintain that motion. Objects would slide forever at a constant speed in a straight line assuming there are no other forces.
Inertia and Mass
- An object with more inertia has a greater mass, meaning it resists changes in motion more.
Weight Calculation
- A 10 kg crate weighs approximately 98 Newtons (Weight = mass x gravity, assuming standard gravity).
Force and Acceleration
- A 2 kg ball accelerating at 25 m/s² experiences a force of 50 Newtons (Force = mass x acceleration).
Acceleration of a Car
- A 1000 kg car with a 200 N net force experiences an acceleration of 0.2 m/s² (Acceleration = force / mass).
Action-Reaction Forces
- If a student pushes on a wall, the wall pushes back on the student with an equal and opposite force.
Leash Force
- A dog pulling on its leash with a 50 N force experiences an equal and opposite 50 N force from the leash (Newton's Third Law).
Free Fall Calculation
- Equations of motion (e.g., v = u + at and s = ut + ½at²) are needed to calculate speed and distance during free fall.
Wolf's Speed
- A wolf running 20 meters in 4 seconds has a speed of 5 m/s (Speed = distance / time).
Projectile Motion Components
- A cannonball fired horizontally at 100 m/s, after falling 20 meters, maintains a horizontal velocity of 100 m/s. The vertical velocity is determined by gravity and time; it is not zero until landing. Use the Pythagorean theorem to find total velocity.
Projectile Velocity Components
- The vertical component of a projectile's velocity is zero at its peak.
- The vertical component of velocity changes due to gravity. The horizontal component stays constant.
Projectile Launch Angle for Maximum Distance
- A 45-degree launch angle maximizes projectile distance, assuming no air resistance; other angles can achieve the same distance.
Tangential Speed Calculation
- A circular disc with a 2 m radius spinning at 5 Hz has a tangential speed of 62.8 m/s (Tangential speed = radius x 2π x frequency).
Centripetal Force Calculation
- A 2000 kg car turning in a 12 m radius circle at 10 m/s experiences a centripetal force of 16,667 N (Centripetal force = mv²/r). This force is created by friction between the tires and the road.
Gravity Calculation
- A 60 kg person on an 8.0 x 10²º kg planet experiences a gravitational pull of approximately 4.9 x 10⁻⁷ N (Gravitational force = G * (mass1 * mass2) / r²).
Impulse and Collision Types
- An object bouncing off a wall requires more impulse than one that stops; bouncing changes momentum more.
Work and Car Speed
- Doubling a car's speed quadruples the work needed to stop it (kinetic energy is proportional to the square of velocity).
Collisions and Velocity
- If two cars collide and stick together, total momentum remains constant; however, the final velocity will depend on the combined masses.
Projectile Height and Kinetic Energy
- For multiple baseballs thrown at the same velocity but various angles off a building, the 90-degree angle leads to the highest KE, neglecting air resistance.
Definitions
Potential Energy
- Stored energy due to position or configuration
Kinetic Energy
- Energy of motion
Power
- Rate at which work is done
Momentum
- Mass in motion
Impulse
- Change in momentum
Conservation of Energy
- Energy cannot be created or destroyed, only transformed.
Conservation of Momentum
- Total momentum in a system remains constant, unless acted upon by external forces.
Elastic Collision
- Collisions where kinetic energy remains constant.
Inelastic Collision
- Collisions where kinetic energy isn't conserved.
Tangential speed/velocity
- Linear speed of a rotating object
Rotational speed
- Number of rotations per unit time
Centripetal force
- Force needed to maintain circular motion
Centrifugal force
- Apparent outward force during circular motion (not a true force).
Action force
- One force in an interaction between two objects
Reaction force
- The equal and opposite force in an interaction between two objects.
Additional Information from the Questions:
- Friction's Absence: Objects would move in a straight line at a constant speed indefinitely.
- Inertia and Mass/Object A: Object A has more mass than Object B.
- Weight of 10 kg Crate: 98 Newtons.
- Force on 2 kg Ball: 50 Newtons.
- Acceleration of 1000 kg Car: 0.2 m/s².
- Reaction Force to Wall Push: The wall pushes back on the student with an equal and opposite force.
- Leash Force: 50 Newtons.
- Free Fall Calculation: Use equations of motion.
- Wolf's Speed: 5 m/s.
- Cannonball Velocity (after 20m): Horizontal velocity remains 100 m/s; vertical velocity is calculated from gravity. Calculate total velocity using Pythagorean Theorem.
- Zero Velocity Component: Vertical velocity component is zero.
- Changing Velocity Component: Vertical velocity component changes due to gravity.
- Maximum Projectile Distance Angle: 45 degrees.
- Tangential Speed of Disc: 62.8 m/s.
- Centripetal Force on Car: 16,667 N, provided by friction between tires and the road.
- Gravitational Pull on Person: 4.9 x 10⁻⁷ N.
- More Impulse: Bouncing off a wall requires more impulse.
- Work and Doubling Speed: Doubling the speed quadruples the work needed.
- Crashing Cars Velocity: Total momentum is conserved; final velocity depends on combined masses.
- Highest KE Baseball Throw: 90-degree angle, assuming no air resistance.
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Description
This quiz covers fundamental concepts of motion and forces including friction, inertia, weight calculation, and Newton's laws. Test your understanding of how forces interact and affect the motion of objects in various scenarios. Perfect for students delving into fundamental physics principles.
