Question

A car accelerates from rest to a velocity of 5 meters/second in 4 seconds. What is its average acceleration over this period of time? A. Its acceleration is 1.25 meters/second. B. Its acceleration is 5 meters/second. C. Its acceleration is 0.8 meters/second. D. Its acceleration is 1.25 meters/second2. E. Its acceleration is 20 meters.

Answer 1

Answer:

The acceleration of the car is  $a=1.25\ m/s^2$.

Explanation:

It is given that,

Initial speed of the car, u = 0

Final speed of the car, v = 5 m/s

Time, t = 4 s

We need to find the average acceleration over this period of time. It is given by the rate of change of velocity. It is given by :

$a=\dfrac{v-u}{t}$

$a=\dfrac{(5-0)\ m/s}{4\ s}$

$a=1.25\ m/s^2$

So, the acceleration of the car is  $a=1.25\ m/s^2$. Hence, the correct option is (D).

Answer 2

The average acceleration is

$\bar a=\dfrac{5\,\frac{\mathrm m}{\mathrm s}-0\,\frac{\mathrm m}{\mathrm s}}{4\,\mathrm s}=1.25\,\dfrac{\mathrm m}{\mathrm s^2}$