AP Physics Unit 5: Momentum

A stationary object explodes, breaking into three pieces of masses m, m, and 3m. The two pieces of mass m move off at right angles to each other with the same magnitude of momentum, mV, as shown in the diagram above. What are the magnitude and direction if the velocity of the piece having mass 3m?

((√2) V)/3 Arrow in negative x and y direction

Two football players with mass 75kg and 100kg run toward each other with speeds of 6m/s and 8m/s respectively. If they grab each other as they collide, the combined speed of the two players just after the collision would be:

2 m/s

Two objects, A and B, initially at rest, are "exploded" apart by the release of a coiled spring that was compressed between them. As they move apart, the velocity ob object A is 5m/s and the velocity of object B is -2m/s. The ratio of the mass of object A to the mass of object B, ma/mb is:

2/5

A ball with mass of 0.5kg and a speed 6m/s collides perpendicularly with a wall and bounces off with a speed of 4m/s in the opposite direction. What is the magnitude of the impulse acting on the ball?

5 N•s

A student obtains data on the magnitude of force applied to an object as a function of time and displays the data on the graph shown. The increase in the momentum of the object between t=0 and t=4 is most nearly:

60 N•s

A 2kg ball collides with the floor at angle theta and rebounds at the same angle and speed. Which of the following vectors represents the impulse exerted on the ball by the floor?

Arrow pointing upwards

Two toy cars with different masses originally at rest are pushed apart by a spring between them. Which of the following statements would be true?

Both toy cars will acquire equal kinetic energies

An open car on a level surface is rilling without frictional loss through a vertical downpour of rain, as shown above. As the cart rolls, an appreciable amount of rainwater accumulates in the cart. The speed of the cart will:

Decrease because of the conservation of momentum

Three objects can only move along a straight, level path. The graphs below show the position, d, of each of the objects plotted as a function of time, t. Graph I: Slope of y=x Graph II: y=d Graph III: y=x^n. The sum of the forces on the object is zero in which of these cases?

I and II only (graph I: y=x & graph II: y=d)

Three objects can only move along a straight, level path. The graphs below show the position, d, of each of the objects plotted as a function of time, t. Graph I: Slope of y=x Graph II: y=d Graph III: y=x^n. The magnitude of the momentum of the object is increasing in which of the cases?

III only (graph III y=x^n)

A rubber ball is held motionless at a height, h0, above a hard floor and is released. Assuming that the collision with the floor is elastic, which one of the following graphs best shows the relationship between the total energy, E, of the ball and its height, h, above the surface?

If E is on the Y and H is on the X, it will be a straight, horizontal line. Y=E

How does an air mattress protect a stunt person landing on the ground after a stunt?

It lengthens the stopping time of the stunt person and reduces the force applied during the landing.

Which of the following is true when an object of mass, m, is moving on a horizontal frictionless surface hits and sticks to an object of mass M>m, which is initially at rest?

The speed of the objects that are stuck together will be less than the initial speed of the less massive object

An object of Mass, M, travels along a horizontal air track at a constant speed, v, collides elastically with an object of identical mass that is initially at rest on the track. Which of the following statements is true for the twi objects after the impact?

The total momentum is Mv and the total kinetic energy is 1/2Mv^2