Question

Starting from rest, a car acquires a speed of 90 km/h in 10 s. Calculate the acceleration of the car.

• A. $2.5cm{s}^{-2}$
• B. $2.5m{s}^{-2}$
• C. $2.5mm{s}^{-2}$
• D. $25m{s}^{-2}$

Answer 1

The correct option is B $2.5m{s}^{-2}$

Given,
Initial velocity $=0m{s}^{-1}$
Final velocity = 90 km/h $=90\times \frac{5}{18}=25m{s}^{-1}$
The first equation of motion is: v = u + at
But, u = 0 (given)
So, v = at
$\Rightarrow a=\frac{v}{t}=\frac{25}{10}=2.5m{s}^{-2}$