Question

A graph is plotted to show the velocity of a car as a function of time. If the graph is a straight line, it means that

• A. the car started at rest
• B. acceleration was constant
• C. acceleration was increasing
• D. velocity was constant

Answer 1

The correct option is B

acceleration was constant

Explanation for the correct option,

1. If the velocity-time graph is a straight line it means the velocity of the bus gradually changes, increases or decreases, at the same rate after each unit time.
2. This also means that the acceleration is a constant every time (the slope is constant for each point in the graph.)

Explanation for the incorrect options,

Option A,

1. If the car started at rest, the straight line should start from the origin.
2. As there is a straight line that does not start from the origin, thus, this option is incorrect.

Option C,

1. If the acceleration changes, then there is a curve on the velocity-time graph.
2. As the graph contains a straight line instead of a curve, thus, this option is incorrect.

Option D,

1. If the value of velocity is constant, then the straight line is parallel to the time axis.
2. As the graph does not contain a straight line parallel to the time axis, thus, this option is incorrect.

Hence, option B is the correct answer.