The motion of a particle is described in the velocity vs.time graph shown in the figure.
Over the nine-second interval shown,we can say that the speed of the particle
A)only increases.
B)only decreases.
C)increases and then decreases.
D)decreases and then increases.
E)remains constant.

Question

The motion of a particle is described in the velocity vs.time graph shown in the figure. 
Over the nine-second interval shown,we can say that the speed of the particle
A)only increases. 
B)only decreases. 
C)increases and then decreases. 
D)decreases and then increases. 
E)remains constant.

Quizplus · Accepted Answer

We can see that the slope of the velocity vs. time graph is negative for the first 3 seconds and positive for the next 3 seconds. Hence, the particle is slowing down for the first 3 seconds and then speeds up for the next 3 seconds. For the last 3 seconds, the slope of the graph again becomes negative indicating that the particle is slowing down. Hence, the speed of the particle first decreases and then increases before decreasing again. Thus, option D is the correct answer.

The Motion of a Particle Is Described in the Velocity