Kinematics

An object is released from rest near a planet's surface. A graph of the acceleration as a function of time for the object is shown for the 4 s after the object is released. The positive direction is considered to be upward. What is the displacement of the object after 2 s?

-10 m

A ball is thrown with an initial speed of 20 m/s at an angle of 60° to the ground. If air resistance is negligible, what is the ball's speed at the instant it reaches its maximum height from the ground?

10 m/s

An object is dropped from the top of a building near Earth's surface. After 2 s, a second identical object is dropped from the same building from the same height. After 4 s, the first object strikes the ground. The graph shows the speeds ν of both objects as a function of time t. What is the approximate acceleration of the center of mass of the two-object system at the moment right before the first object reaches the ground?

10 m/s^2

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

20 m

A ball is released from rest from the twentieth floor of a building. After 1 s, the ball has fallen one floor such that it is directly outside the nineteenth-floor window. The floors are evenly spaced. Assume air resistance is negligible. What is the number of floors the ball would fall in 3s after it is released from the twentieth floor?

7 to 10 floors

Balls 1 and 2 are each thrown horizontally from the same height above level ground, but ball 2 has a greater initial velocity after leaving the thrower's hand. If air resistance is negligible, how do the accelerations of the balls and the times it takes them to hit the ground compare?

Acceleration a: Equal Time to hit ground: Equal

Object 1 and object 2 travel across a horizontal surface, and their horizontal velocity as a function of time is shown in the graph. Which of the following statements is correct about the two-object system?

After 2s, object 1 travels a greater distance than object 2 travels.

An object begins at position x = 0 and moves one-dimensionally along the x-axis with a velocity v expressed as a function of time t according to the graph above. At what time does the object pass through x = 0 again?

Between 20 s and 30 s

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 area bound by the horizontal axis and the curve from 0 s0 s to 5 s Using Average Speed=total distance/total and multiplying the average speed of 5 m/s by a total time of 5 s

Two students want to determine the speed at which a ball is released when thrown vertically upward into the air. One student throws the ball into the air while the other student measures the total time that the ball is in the air. The students use a meterstick to measure the release height of the ball. Which of the following equations should the students use to determine the speed at which the ball was released?

Use y=y0+vy0t+12ayt^2 from the moment in time in which the ball was released to the moment in time in which the ball hits the ground.

Object A is released from rest at height h. At the same instant, object B is thrown downward from the same location. Which of the following graphs of speed of v as a function of time t is correct for the two objects?

line B is above line A, they are parallels only line a starts from origin option b

A lion is running at constant speed toward a gazelle that is standing still, as shown in the top figure above. After several seconds, the gazelle notices the lion and accelerates directly toward him, hoping to pass the lion and force him to reverse direction. As the gazelle accelerates toward and past the lion, the lion changes direction and accelerates in pursuit of the gazelle. The lion and the gazelle eventually each reach constant but different speeds. Which of the following sets of graphs shows a reasonable representation of the velocities of the lion and the gazelle as functions of time?

lion starts negative then goes positive velocity gazelle starts 0 then goes positive The graph for the lion shows an initial velocity toward the left, slowing down to zero, and speeding up to the right and reaching a constant velocity to the right. The graph for the gazelle shows the gazelle initially at rest for a period of time, then speeding up to the right, and reaching a constant velocity toward the right.