Question

Kinetic energy of a particle initially at rest moving in a straight line varies with time $t$ as $k=$ $4t^2$. The force acting on the particle is:

• A. is increasing.
  
• B. is constant.
  
• C. is decreasing.
  
• D. first increases then decreases
  

Answer 1

The correct option is B is constant.

$k=4t^2$

$\Rightarrow \frac{1}{2}m{v}^2$ $=$ $4t^2$

$\Rightarrow v=c^{\prime }t$ (Where c' is constant)

Comparing with kinematics equation $v=u+at$

Acceleration of particle is constant $\Rightarrow F=$ Constant