Question

(a) A cyclist doubles his speed. How will his kinetic energy change? $\left[1\text{Mark}\right]$

(b)Can a body possess mechanical energy even when it is not in motion ? Explain your answer with an example$\left[2\text{Marks}\right]$

Answer 1

(a) When a cyclist doubles his speed, his kinetic energy increases four times:

KE $=\frac{1}{2}\times \text{m}\times {\text{v}}^2$

$\left[1\text{Mark}\right]$

(b)Yes, a body possesses energy even when it is not in motion; Consider a body raised to a certain height say h. Its velocity is zero.$\left[1\text{Mark}\right]$
Kinetic energy will be zero but the body will have. P.E. = mgh.
Thus, a body may possess energy even though it is not in motion.
$\left[1\text{Mark}\right]$