AP Physics Opener 10/13

A student throws a rock horizontally from the edge of a cliff that is 20 m high. The rock has an initial speed of 10 m/s. If air resistance is negligible, the distance from the base of the cliff to where the rock hits the level ground below the cliff is most nearly

• 5 m

• 10 m

• 20m

• 40 m

• 200 m

A cart is constrained to move along a straight line. A varying net force along the direction of motion is exerted on the cart. The cart’s velocity v as a function of time t is shown in the graph above. The five labeled points divide the graph into four sections.

Which of the following correctly ranks the magnitude of the average acceleration of the cart during the four sections of the graph?

• aCD > aAB > aBC > aDE

• aBC > aAB > aCD > aDE

• aAB > aBC > aDE > aCD

• aCD > aAB > aDE > aBC

A student performs an experiment in which the horizontal position of a toy car is recorded on ticker tape from a device that places dots on the tape in equal time intervals. The series of dots in the figure represents the motion of an object moving from the negative direction to the positive direction along the horizontal direction. The time interval between each recorded dot is 1s. Which of the following experiments could the student have conducted to create the data shown on the ticker tape?

• A toy car that initially increases its speed, travels at a constant speed, and then increases its speed again.

• A toy car that initially increases its speed, travels at a constant speed, and then decreases its speed.

• A toy car that initially decreases its speed, stops, and then increases its speed.

• A toy car that initially decreases its speed, travels at a constant speed, and then increases its speed.

An object travels along a straight line across a horizontal surface, and its motion is described by the velocity versus time graph shown in the figure. Which of the following methods will determine the total displacement of the object between 0 s and 5 s? Select two answers.

• Finding the slope of the line between 0 s to 5 s

• Dividing the change in velocity between 0 s

  to 5 s by the change in time

• Finding the area bound by the horizontal axis and the curve from 0 s to 5 s

• 

Two objects, X and Y, accelerate from rest with the same constant acceleration. Object X accelerates for twice the time as object Y. Which of the following is true of these objects at the end of their respective periods of acceleration?

• Object X is moving at the same speed as object Y.

• Object X is moving four times faster than object Y.

• Object X has traveled the same distance as object Y.

• Object X has traveled twice as far as object Y.

• Object X has traveled four times as far as object Y.