Question

A body of mass 2 kg is at rest.What should be the magnitude of force which will make the body move with a speed of 30 m/s at the end of 1 s?

Answer 1

$$\textbf{Given:}\ $$Mass $$=2$$ kg, Initial velocity $$u=0$$, Final velocity $$v=30\ m/s$$, Time $$t=1\ s$$

$$\textbf{Step 1: Equation of motion for finding the acceleration}$$

As the acceleration is constant, so using the first equation of motion,

$$v= u+at$$

So, Acceleration $$a=\dfrac{v-u}{t}=\dfrac{30-0}{1}=30 m/s^2$$

$$\textbf{Step 2: Newton's Second law for finding the Force}$$

Force, $$F= m \times a =2 \times 30=60$$ N

Hence 60 N force is required.