Question

How much work must be done by a force on $50$$kg$ body in order to accelerate it from rest to $20m/s$ in $10$$s$ ?

• A. ${10}^3$$J$
• B. ${10}^4$$J$
• C. $2\times {10}^3$$J$
• D. $4\times {10}^4$$J$

Answer 1

The correct option is B ${10}^4$$J$

Acceleration that causes the given rise in speed in given time = $a=\frac{v}{t}=\frac{20m/s}{10s}=2m/s^2$

Thus, force acting on the body = $F=ma=100N$

Distance travelled in the given time = $s=\frac{1}{2}a{t}^2=100m$

Thus, work done in given time = $F.s={10}^{4}J$