Question

A constant force acting on a body of mass of 5kg change its speed from 5 $m{s}^{-1}$ to 10 $m{s}^{-1}$ in 10 s without changing the direction of motion. The force acting on the body is

• A. 1.5 N
• B. 2 N
• C. 2.5 N
• D. 5 n

Answer 1

The correct option is C 2.5 N

Here, m=5 kg, u=5 $m{s}^{-1}$, v=10 $m{s}^{-1}$, t= 10s
Using v=u+at
$a=\frac{v-u}{t}=\frac{(10-5)m{s}^{-1}}{10s}=0.5m{s}^{-2}$
As F=ma
$\therefore F=\left(5kg\right)\left(0.5m{s}^{-2}\right)=2.5N$