beginning of content:
SAT Subject Test
A block is pulled along a horizontal surface with a constant horizontal force of magnitude 
. The surface exerts a frictional force of constant magnitude 
on the block. The graph of speed 
as a function of time 
for the block is shown above.
Which of the following shows the graph of acceleration a as a function of time for the block?
Select an Answer
Correct Answer:
No
Correct Answer:
Yes
Correct Answer:
No
Correct Answer:
No
Correct Answer:
No
View Correct Answer
The correct answer is (B), a constant acceleration. At each instant the acceleration is the slope of the velocity graph. Since the velocity curve is a straight line that has constant slope, the acceleration is constant. Alternately, the description indicates that both the force pulling the block and the frictional force are constant. Acceleration is force divided by mass, so it also must be constant.
Question Difficulty:
easy