Question

A body of mass 'm' moving with a constant speed
'v' changes its direction of motion such that the
velocity changes by 12 v. Change in its kinetic en-
ergy is
(1)
my2
(2) my2
2
(3)
2 mv2
(4) zero​

Answer 1

Question

A body of mass 'm' moving with a constant speed  'v' changes its direction of motion such that the  velocity changes by 12 v.

Calculate the change in its kinetic energy.

Solution

Kinetic Energy Of a body = $\dfrac{1}{2} \times m \times v$

The mass of the required body is m.

Its velocity varies from v to 12v .

Hence Initial Kinetic Energy = $\dfrac{1}{2} mv$

Final kinetic energy = $\dfrac{1}{2} m . 12v = 6mv$

Net change in kinetic energy = Final Kinetic Energy - Initial Kinetic Energy

$= 6mv - \dfrac{1}{2} mv \\ \\ = \dfrac{11}{2} mv \ ........ [ A ]$