AP Physics 1 Unit 5 Progress Check A
A 9000kg rock slides on a horizontal surface with negligible friction at 3m/s toward a 3000kg rock that is at rest, as shown in Figure 1. A collision occurs such that the two rocks remain stuck together and travel with a common final speed vf , as shown in Figure 2. What is the speed vf of the two-object system after the collision?
2.25 m/s
A student performs several experiments in which two carts collide as they travel along a horizontal surface. Cart X and Cart Y both have a mass of 1kg. Data collected from the three experiments are shown in the table. During which experiment does the center of mass of the system of two carts have the greatest change in its momentum?
All experiments have the same change in momentum for the center of mass of the system of two carts.
Object X collides into object Y and exerts a force on object Y while both objects are in contact. A graph of the force that object X exerts on object Y is shown. How could the graph be used to determine the change in momentum of object Y during the collision?
By determining the area bound by the curve and the horizontal axis from 0s0s to 0.01s
Astronaut X of mass 50kg floats next to Astronaut Y of mass 100kg while in space, as shown in the figure. The positive direction is shown. Astronaut X applies a force against Astronaut Y such that the kinetic energy of each astronaut as a function of time is shown in the graph. What is the change in momentum of the two-astronaut system and the change in momentum of each astronaut from immediately before the force was applied to immediately after the force was applied?
Change in Momentum of the System (kg⋅m/s) 0 Change in Momentum of Astronaut X (kg⋅m/s)(kg⋅m/s) -100 Change in Momentum of Astronaut Y (kg⋅m/s)(kg⋅m/s) 100
A block travels across a horizontal surface in which frictional forces are not considered to be negligible, as shown in the figure. Which of the following quantities should a student measure to verify that the direction of the frictional force exerted on the block from the surface is in the same direction as the change in momentum of the block? Select two answers. Justify your selections.
The initial velocity, because the initial momentum of the block is proportional to the final momentum of the block. The final velocity, because the initial momentum of the block is proportional to the final momentum of the block.
Two objects of the same mass travel in opposite directions along a horizontal surface. Object X has a speed of 5ms and object Y has a speed of 5ms, as shown in the figure. After a period of time, object X collides with object Y. In scenario 1, the objects stick together after the collision. In scenario 2, the objects do not stick together after the collision. Which of the following claims is true regarding how the outcome of scenario 1 is different from the outcome of scenario 2?
The kinetic energy of the system in scenario 1 will be less than that in scenario 2 after the collision.
An experiment is conducted in which a cart travels across a horizontal surface and collides with a wall. Data collected from the experiment are used to create the graph of the cart's velocity as a function of time. All frictional forces are considered to be negligible. Which data from the graph should the student use to determine the direction of the net force exerted on the cart and the direction of the change in momentum of the cart from the time intervals of A to B?
The slope of the line from AA to BB, because that will provide information about the acceleration of the cart.
A toy car of mass 2kg travels along a horizontal surface with negligible friction at a speed of 1.0ms. The car then collides with a vertical wall. The wall applies a force of magnitude 20N for 0.2s on the toy car. Which of the following predicts the motion of the toy car immediately after the collision?
The speed of the car will remain the same, and the car will travel in the opposite direction.
Block X and block Y are tied together by a rope. The system containing block X and block Y is released from rest on a ramp, as shown in the figure. Block Y has a smaller mass than block X. Which of the following claims is correct regarding the momentum of the system containing only block X and the system that contains block X and block Y?
The system containing block XX is an open system, and the system of both blocks is an open system.
A mass M1 slides along a horizontal surface and collides with and sticks to a mass M2 that is initially at rest at the bottom of a ramp, as shown in Figure 1. Frictional forces between the masses, the surface, and the ramp are considered to be negligible. After the collision, masses M1 and M2 slide together up the curved ramp as a total mass of M12 , as shown in Figure 2. The two masses eventually come to rest at their highest position along the ramp. Which of the following claims is correct regarding the momentum of the system of mass M1 and the system of mass M1 and M2 in terms of their momenta?
The system of mass M1M1 is an open system, and the system of mass M1M1 and M2M2 is an open system.
A cart is attached to a hanging block by a string that passes over a pulley, as shown in the figure. The pulley has negligible friction in its axle and negligible mass. A student must determine the change in momentum of the cart as it is pulled across the horizontal surface from the moment the cart is released from rest to the moment immediately before the cart collides with the pulley. Which of the following lists the measuring devices that are needed to determine the change in momentum of the cart?
Timer, mass balance, and meterstick
A student conducts an experiment in which a cart is pulled by a variable applied force during a 2 s time interval. In trial 1, the student exerts the force on a cart of mass M. In trial 2, the student exerts the force on a cart of mass 3M. In trial 3, the student exerts the force on a cart of 5M. In which trial will the cart experience the greatest change in momentum from 0 s to 2 s?
Trial 3
During an experiment, a toy car accelerates forward for a total time of 5s. Which of the following procedures could a student use to determine the average net force exerted on the car during the 5s that the car accelerates?
Use a balance to determine the mass of the car. Use a motion sensor to measure the speed of the car at a time of 0s and a time of 5s.
A block of mass of 10kg travels in the positive direction along a surface with negligible friction. The block has an initial momentum 18kg⋅ms. The block collides with an object of an unknown mass that is at rest. The force exerted on the block as a function of time is shown on the graph. Which of the following best predicts the speed and direction of the block immediately after the collision?
speed decreases direction same
Two objects of the same mass travel in opposite directions along a horizontal surface. Object X has a speed of 5ms and object Y has a speed of 5ms, as shown in the figure. After a period of time, object X collides with object Y. In scenario 1, the objects stick together after the collision. In scenario 2, the objects do not stick together after the collision. Consider scenario 1. Is the object X-object Y system open or closed? Predict whether both the momentum and the kinetic energy of the system will be the same or different after the collision.
system closed momentum same KE changes
A force is applied to a 2kg object, and measurements of the force as a function of time are shown. The force is the only force exerted on the object and is applied in the direction of the object's velocity. Which of the following could represent the initial velocity, v0, and the final velocity, vf, of the object?
v0=4 vf=6
Block X travels towards Block Y that is initially at rest, as shown in the figure, and eventually collides with Block Y. Which of the following diagrams represents the final velocities for Block X and Block Y after the collision if the collision is elastic?
x= 2.4 m/s y= 6.4 m/s
