Question

During a collision with another car, the occupants of a minivan initially travelling at 4.0 m/s come to a complete stop in 0.5 s. What was the acceleration of the occupants of the minivan?



a) 8.0 m/s2



b) –8.0 m/s2



c) 2.0 m/s2



d) –2.0 m/s2

Answer 1

Answer: b) - 8.0 $m/s^{2}$

Explanation: Acceleration is a vector indicating a rate an object's velocity changes over time:

a = $\frac{v}{t}$

and its SI unit is $m/s^{2}$

For the minivan to stop, it takes a period of 0.5s:

a = $\frac{4.0}{0.5}$

a = 8.0 $m/s^{2}$

As a vector, acceleration has magnitude (8$m/s^{2}$) and direction. Since it is stopping, the minivan has a direction opposite to the other car, which means acceleration is negative. So: a = $- 8.0 m/s^{2}$.