Question bank/JEE Main/Physics

Kinetic energy of a particle of mass 2 kg moving along a circle
varies with time t as $K = 3t^{2}$, where t in second and K is in
Joules. Then rate at which work is being done on particle at t=1 s in
watt is

A6B4C5D2

Show answer and solution▾

$K = \frac{1}{2}{mv}^{2} = 3t^{2}$
$v = \sqrt{3}t$
$a_{t} = dv/dt = \sqrt{3}$
$= ma_{t}v$
$= 2.\sqrt{3} \cdot \sqrt{3} \times 1 = 6watt$

Source: Grass-G / P-18 Physics paper 27 Nov Third.docx