Exam 2: Describing Motion: Kinematics in One Dimension

The velocity of an object as a function of time is given by v(t) = -3.0 m/s - (2.0 m/s²) t + (1.0 m/s³) t². Determine the instantaneous acceleration at time t = 2.00 s.

The area under a curve in a velocity versus time graph gives

Which statement is correct about the relationship between the average speed and the magnitude of the average velocity for any motion?

It is possible to have a zero acceleration, and still be moving.

A rock is dropped from a vertical cliff. The rock takes 7.00 s to reach the ground below the cliff. What is the height of the cliff?

FIGURE 2-7 -Fig. 2-7 represents the velocity of a particle as it travels along the x-axis. At what value of t is the instantaneous acceleration equal to zero?

Two objects are dropped from a bridge, an interval of 1.0 s apart. During the time that both objects continue to fall, their separation

To determine the height of a flagpole, Abby throws a ball straight up and times it. She sees that the ball goes by the top of the pole after 0.5 s and then reaches the top of the pole again after a total elapsed time of 4.1 s. How high is the pole above the point where the ball was launched?

If the position versus time graph of an object is a horizontal line, the object is

At a given instant, the acceleration of a certain particle is zero. This means that

FIGURE 2-4 -A graph of position as a function of time is shown in Fig. 2-4. During which time interval could the object be possibly moving with non-zero constant acceleration?

A jet fighter plane is launched from a catapult on an aircraft carrier. It reaches a speed of 42 m/s at the end of the catapult, and this requires 2.0 s. Assuming the acceleration is constant, what is the length of the catapult?

When the velocity and acceleration of an object have opposite signs, the speed of the object increases.

FIGURE 2-1 -Fig. 2-1 shows the position of an object as a function of time. During which time interval is the object at rest between 0.0 s and 9.0 s?

FIGURE 2-10 -Fig. 2-10 shows the position of an object as a function of time. What is the displacement of the object between time and time t = 9.0 s?

Which statement below about the distance between the starting and ending positions and the displacement between the starting and ending positions is correct?

When the velocity and acceleration of an object have the same sign, the speed of the object increases.

An object is dropped from a bridge. A second object is thrown downwards 1.00 s later. They both reach the water 20.0 m below at the same instant. What was the initial speed of the second object?

Two objects are thrown from the top of a tall building. One is thrown up, and the other is thrown down, both with the same initial speed. What are their speeds when they hit the street?

Which of the following graphs could possibly represent the motion as a function of time of an object in free fall?