Ap Physics 1 Unit 1 Progress Check

Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. After Rock Y is released from rest several seconds after Rock X is released from rest, what happens to the separation distance S between the rocks as they fall but before they reach the ground, and why? Take the positive direction to be downward.

S increases because at all times Rock X falls with a greater speed than Rock Y.

Identical objects, Object X and Object Y, are tied together by a string and placed at rest on an incline, as shown in the figure. The distance between the center of mass of each object is 2m. The system of the two objects is released from rest, and a graph of the system's center of mass velocity as a function of time is shown. Based on the data, approximately how much time will it take the center of mass of Object X to reach point J near the bottom of the incline?

3 s

A ball traveling at a speed ν0 rolls off a desk and lands at a horizontal distance x0 away from the desk, as shown in the figure. The ball is then rolled off of the same desk at a speed of 3 v0. At what horizontal distance will the ball land from the table?

3x0

A student drops a rock from rest at a distance h above the ground such that the rock hits the ground at time t0. At what distance above the ground should the rock be dropped such that it hits the ground at a time 2t0 after it is released from rest?

4h

Car X and car Y travel on a horizontal surface along different parallel, straight paths. Each car's velocity as a function of time is shown in the graph. Which of the following claims is correct about car X and car Y?

Both car X and car Y travel in the same direction.

An object is launched upward at angle θ0 above the horizontal with a speed of v0. The trajectory and three positions of the object, X, Y, and Z, are shown in the figure. Position X is higher than position Z with respect to the ground, and position Y is at the object's maximum vertical position. Which of the following claims is correct about the system that consists of only the object?

The object's acceleration is the same at positions X, Y, and Z.

A student uses a motion sensor to collect data of the velocity of an object as a function of time during two experimental trials, as shown. In which trial does the object have the greatest magnitude of acceleration, and in which trial does the object travel the greatest distance?

Trial 2; trial 1

A student must design an experiment to determine the acceleration of a cart that rolls down a small incline after it is released from rest. The student has access to a timer, a meterstick, and a slow-motion camera that takes a photograph every 160 of a second. The angle that the incline makes with the horizontal is unknown, and the length of the incline is unknown. Which of the following procedures could the student use to determine the cart's acceleration? Select two answers.

Use the timer to record the time it takes the cart to travel alongside a meterstick that is attached to the incline. Use the slow-motion camera to film the cart as it rolls down the incline alongside a meterstick that is attached to the incline.

The table shows the vertical position as a function of time for an object that is dropped from a height of 5 m. A student must determine the acceleration of the object. Which of the following procedures could the student use to make the determination? Justify your selections. Select two answers.

Use y=y0+vy0t+12ayt2, since all quantities are known except for the acceleration due to gravity. Create a position-versus-time graph of the ball's motion, and use the data to create a velocity-versus-time graph of the ball's motion, since the slope of the velocity-versus-time graph represents the acceleration.

Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. Which of the following graphs correctly shows the vertical velocity of rock X as a function of time? Take the positive direction to be upward.

negative slope, straight line, has a point at the origin

An object travels along a straight, horizontal surface with an initial speed of 2 ms. The position of the object as a function of time is given in the table. Which of the following graphs represents the object's velocity as a function of time?

positive non zero slope line

Rock X is released from rest at the top of a cliff that is on Earth. A short time later, Rock Y is released from rest from the same location as Rock X. Both rocks fall for several seconds before landing on the ground directly below the cliff. Frictional forces are considered to be negligible. Which of the following graphs best represents the vertical displacement of Rock X as a function of time starting from immediately after the rock is released from rest? Take the positive direction to be downward.

smiley parabola with a point at the origin

An object travels along a straight, horizontal surface with an initial speed of 2 ms. The velocity of the object as a function of time is given in the table above. Which of the following graphs represents the object's acceleration as a function of time?

straight line at 2 (slope 0)

Two objects, object X and object Y, are held together by a light string and are released from rest near a planet's surface in the orientation that is shown in the figure. Object X has a greater mass than object Y. A graph of the acceleration as a function of time for the system's center of mass is shown for the 4s. The positive direction is considered to be upward. How does the speed of object X vx compare to that of the system's speed vs after the objects have fallen for 4s ?

vx=vs

An object is held at an unknown height above Earth's surface, where the acceleration due to gravity of the object is considered to be constant. After the object is released from rest, a student must determine the object's speed the instant the object makes contact with the ground. Which of the following equations could the student use to determine the object's speed by using the fewest measuring tools if the student does not have access to a motion sensor? Select two answers.

vx=vx0+axt v2x=v2x0+2ax(x−x0)

Toy car W travels across a horizontal surface with an acceleration of aw after starting from rest. Toy car Z travels across the same surface toward car W with an acceleration of az after starting from rest. Car W is separated from car Z by a distance d. Which of the following pairs of equations could be used to determine the location on the horizontal surface where the two cars will meet, and why?

x=x0+v0xt+12axt2 for car WW, and x=x0+v0xt+12axt2 for car Z. Since the cars will meet at the same time, solving for t in one equation and placing the new expression for t into the other equation will eliminate all unknown variables except x.