Question

A body of mass 2 kg starts from rest and moves with uniform acceleration. It acquires a velocity of 20 m/s in 4 seconds.The power exerted on the body in 2 seconds is

• A. $500Watts$
• B. $100Watts$
• C. $50Watts$
• D. $200Watts$

Answer 1

The correct option is C $50Watts$

$Work=\text{change in K.E}=\frac{1}{2}m(v^2-u^2)v=u+at20=0+a\times 4a=5m/s^{2}v=u+at=0+5\times 2=10m/swork=\frac{1}{2}\times 2\times 10\times 10=100J\text{From work Energy theorem, work}=\frac{1}{2}m{v}^{2}Work=\frac{1}{2}\times 2\times 10\times 10=100JPower=\frac{Work}{time}=\frac{100}{2}=50watt$