Physics: Branches, Motion and Velocity

Branches of Physics

• Mechanics deals with the motion of objects and the forces that cause them.
• Thermodynamics studies heat and its relationship to other forms of energy.
• Optics explores the properties and behavior of light.
• Acoustics is a branch of physics that focuses on the study of sound and its properties.
• Nuclear physics investigates the structure, properties, and interactions of atomic nuclei.
• Electromagnetism studies electricity and magnetism and their interactions.

Motion and Velocity

• For a car traveling at a constant velocity from left to right, pushing the accelerator increases velocity.
• Pushing down on the brakes will cause a negative acceleration.

Calculating Initial Speed

• Initial speed can be calculated using acceleration, final speed, and time.
• For example, a motorcycle accelerating at 4.0 m/s² to a speed of 35 m/s in 5.0 s had an initial speed of 15 m/s.

Displacement vs. Distance

• Displacement considers direction and is the net change in position.
• Distance is the total length of the path traveled, regardless of direction.
• For instance, if Tiana jogs 1.5 km, then 2.4 km in the opposite direction, and 0.7 km back, her displacement is 0.2 km
• Distance traveled is 4.6 km.

Constant Acceleration

• An object moving along the x-axis with a constant acceleration of 6 m/s² and an initial velocity of -24 m/s has its position determined by kinematic equations.
• If starting at x = 6 m at t = 0 s, the position when its velocity is zero is -42 m.

Force

• When a cat of mass 5kg jumps on a dining table of mass 30kg, the tabletop applies force to the cat.
• The average force that the table applies to the cat is 50 N.
• Newton stated that for an object of weight 589 N accelerating at 4m/s², the force of the push is 240N.

Collisions

• In head-on collisions, the car with more mass experiences less acceleration.
• The forces exchanged between the two cars are the same.

Fundamental Forces

• Weak nuclear force is involved in radioactive decay.

Projectile Motion

• Maximum peak can be achieved by throwing the ball at 90 degrees.
• For a ball thrown horizontally, with negligible air resistance, the acceleration remains constant at 9.8 m/s² downwards.

Newton's Third Law

• According to Newton's Third Law, a swimmer applies a force on the water, and the water applies an equal and opposite force on the swimmer.

Vector Dot Product

• Two vectors, A and B, with magnitudes of 4 units and 5 units respectively, at an angle of 60 degrees, have a dot product of 10.

Average Speed

• The average speed of a car traveling 60 km at 60 km/h and then 30 km at 30 km/h is 40 km/h.

Uniform Acceleration

• A particle moving with uniform acceleration in a straight line that goes from 5 m/s to 45.5 m/s in 20 seconds has an acceleration of 2.03 m/s².

Projectile Time

• A ball thrown horizontally from 6 m with an initial speed of 30 m/s will take approximately 1.11 s to reach the ground.

Boat Speed

• A boat travels 80 km north and 60 km east and has an average speed of 140 km/h.

Projectile Motion Truths

• The horizontal component of the velocity of a projectile is the same throughout its flight.

Displacement Direction

• Determine the magnitude and direction of displacement from warehouse using vector summation.
• For example, the displacement is 4.19 km, 72.6° north of west if a truck travels 2.60 km north, 1.25 km west, and 1.40 km north.

Kinetic Energy

• An object with non-zero energy can be a satellite in geosynchronous orbit
• Kinetic energy is always positive.
• A jet airplane flying at its maximum speed possesses the largest kinetic energy.
• Kinetic energy increases when a ball starts from rest and freely rolls downhill.

Work

• If a concrete block is pulled 7.0 m across a frictionless surface by a rope with a tension of 40 N, and the net work done is 247 J, the rope angle is 28°.

Work and Energy

• There is zero net work done when a box is pulled across a rough floor at constant velocity.

Momentum

• While falling, a rock's speed and an equal increases in momentum for each falling meter.
• The momentum of an object can be found by multiplying it's mass by it's velocity.
• For example, Jennifer has a momentum of 68.6 kg m/s when walking at 1.22 m/s and weighing 552 N.
• A 1.0-kg ball with a velocity of 12 m/s downward that bounces up with a velocity of 12 m/s upward experiences a change in momentum of 24 kg m/s, upward.
• Linear momentum is not conserved when a golf ball is struck by a club
• The vector sum of the linear momenta of the fragments must be zero when a stationary bomb explodes in space with zero net force due to gravity.

Fragmented Objects

• When an object of mass 3m explodes into fragments of mass m and 2m, the smaller fragment will have twice the speed of the larger fragment.

Kinetic Energy Transfer

• A 2-kg stone that falls 100 meters and makes a collision will have 2000 joules transferred in this process.

Momentum True Statements

• When a tennis ball with a velocity of 12 m/s downwards strikes the ground and bounces up at 12 m/s the momentum of the ball and the earth both change

Collisions

• A 3.0-kg cart moving to the right at 1.0 m/s collides with a 5.0-kg cart moving to the left at 2.0 m/s, the final velocity of the 5.0-kg cart is zero m/s.
• When a 1000-kg car at 20 m/s east collides with a 1500-kg car at 10 m/s west, the common velocity of the cars after the collision is 4 m/s, east.
• Different types of collisions between interacting bodies are categorized on the basis of kinetic energy conservation.

Motion in Space

• An astronaut orbits the earth at a height equal to the earth's radius: her weight is approximately one-fourth on earth.
• Perceived weightlessness in space is due to spaceship free fall.

Rotational Motion

• Helicopter blades rotate in opposite directions to cancel the torques, preventing the body from rotating.
• Assuming a planet with the same mass but double the radius would have two times greater of angular momentum if it rotates at the same rate as Earth
• The angular velocity of the merry-go-round decreases when a child jumps off radially.
• Tangential speed equals 2 m/s if the object with radius 0.5 meters accelerates to 10 rad/s in 5 seconds at t=2 seconds.
• An object with a linear speed of 6 m/s along a radius of 3 meters has a centripetal acceleration of 12 m/s².
• Centripetal and tangential acceleration vectors are perpendicular to each other.

Circular Motion

• A car with a radius of 500 meters completing one lap in 60 seconds has an angular speed of approximately 0.10 rad/s.
• Competitive divers extend their limbs to increase their moment of inertia and slow their rotation for a controlled entry.
• On a body of 1kg is tied to the end of a string 1 m long and is whirled in a vertical circle with a constant speed of 4 m/s when is the tension in the string 6.2 N
• Uniform circular motion is considered accelerated motion because the motion accelerates due to the change in velocity.
• Stone is tied to a string and whirled in a circle, the centripetal force provide the tension in the string
• The passengers are thrown outwards when a car negotiates a curve.

Particle angular displacement

• A particle has an angular displacement of 21 radians if moving in a radius of 0.5 m with an initial angular velocity of 4 rad/s and a constant angular acceleration of 2 rad/s2 when t= 3 seconds.
• When the radius is halved and the velocity has increased by a factor of 2, its centripetal will increases by a factor of 8
• A sudden stop in earths rotation would cause any objects at the equator to get thrown eastward.

Centripetal Force

• Centripetal force performs no work.
• In case of planets the gravitational force provides the acceleration.
• When a car moves with a uniform speed of 2 ms-2 in a circle of radius 0.4. its angular speed is 5 rad. s-1
• Elliptical path is a body with constant velocity can have.
• If an object is moving in a circle with a radius of 2 meters at a constant speed and the centripetal acceleration is 8 m/s, its angular velocity is 2 rad/s.
• After 5 seconds a wheel starts from rest and accelerates uniformly to an angular velocity of 20 rad/s , the wheel has angular acceleration of 4 rad/s
• Torque acting on a body determines angular acceleration.
• A central force can't produce torque
• It is easier to turn a steering wheel with both hands than with a single hand because couple acts on the wheel
• Constant condition of momentum change is determined by rate of change momentum.
• One condition for the conservation of momentum is a system must be closed with no external forces act on it.
• Objects after an inelastic collision causes the objects to stick together and move with a common velocity.
• After a 3 kg object moving at 4 m/s to the right collides elastically with a 5 kg object moving at 2 m/s to the left the final velocity of the 3 kg object is -3.5 m/s.
• The stationary 3 kg object increases to 2 m/s after a A 2 kg object moving at 5 m/s collides elastically.
• An increased time interval over which a constant force is applied will increases the impulse.
• The change in momentum is 50 kg.m/s when a 10 kg object experiences an impulse of 50 N.s.
• When different masses collide, the total momentum remains constant.
• If a ball is dropped from a height bounces off the ground in perfect elastic, it means it Remains constant before and after the collision.
• Elastic collisions conserve kinetic energy.
• A hose ejects water at a rate of 2 kg/s with a velocity of 10 m/s, directed horizontally against a stationary wall water on the wall
• The magnitude of the force exerted by the wall is 20 N
• A system consists of two carts on a frictionless track. Cart A has a mass of 2 kg and moves at 3 m/s to the right. Cart B has a mass of 3 kg and is initially at rest. If the carts collide and stick together, what is the final velocity of the combined carts
• Is 1.2 m/s to the right
• If a rubber ball and a steel ball, both of the same mass, are dropped onto a steel plate, the steel ball imparts a greater impulse to the steel plate
• 6525 N is the average force exerted if a baseball is pitched with 40 m/s, hitting the bat after 0.002 second and sending the ball back with a velocity of 50 m/s.
• Skater B has a velocity of 1.5 m/s in the opposite direction to Skater A when he travels with a velocity of 2m/s with a mass of 60 kg after two ice skaters initially at rest, push off against one another with a mass of 80 kg.
• In order when 50 N force results in 433 newton meters the angle with the horizontal is 30
• At 50° below pushing 60N when pushing a lawn mower. the work done by the person on the mower is 720.0 J
• Always positive: About kinetic energy, pick the true statement:
• One key modern area of nuclear research is the study behavior of quarks and gluons.

Stellar Life Cycles

• Studying the formation and evolution of stars requires working in astrophysics, a branch of physics.

Solid and Applied Physics

• Superconductivity relates to solid-state physics.
• Designing machines with Magnetic Resonance Imaging (MRI) relies on electromagnetism.

Sound in Physics

• Doppler Effect is primarily studied in acoustics.

Light in Physics

• Fiber optic communication is best explained by optics.

Car Speed

• A car travels 100 miles to city A in 2 hours, then travels 200 miles to city B in 3 hours with an average speed of 60 mph.

Distance

• With a force of 60N traveling 12 m across a yard, the work by the person is 462.1 newton meters
• At 2 m/s2, A racer accelerates from rest at a constant rate of 3.0 and traveled by the end of 13 seconds is 253.5 newton meters

Particle Velocity

• A particle's velocity at t = 5 seconds is 9 ft/s for x axis as defined by the by x(t) = t^2 - t + 8.

Particle Position

• The acceleration of x(t) = 3.4t^3 is 102 m/s²

Constant Acceleration and Speed

• A car has a speed of 24 meters per second when it accelerates from 6 m/s² after 4 seconds.

Acceleration increase

• The acceleration of a truck is 0.411 m/s² when increasing from 13 km/hr to 50 km/hr in 25 seconds.

Ball hit time

• The time it takes for a ball is 3.5 seconds, if it drops at 60 m

Distance

• A jogger travels 40 meters North, and 30 m East with a magnitude of 50 newton
• Moving 60 in 2 hours along with moving 30 in 8 hours is with an average of 9 m/h, kilometers

Momentum

• In a car the is variable due to the fact of constant change
• Which moving involves and is with an accelerated
• In a car moving along a circular track

Acceleration

• The mean 5 meters with A car which can be at 25 for up to 5.083 meter

Time in air

• The amount of time a tennis ball remains in the air up to 4.59s.

Vectors

• To solve exact calculations determine the two vector product.
• • -30i -19j +33k in vector b with the formula b (5i + 6j + 8k) and vector a (3i

Static Friction

• For an object weighing 20 on a cement floor, with a static friction of about 25%, has 49N force strength required for the box to move
• Static can be generally a great value

Friction

• Kinetic will not depend on Aera

Free Air

• constant acceleration and the free force velocity