A body of mass 5 kg is moving with a momentum of 10 kg m s - 1 . Now a force of 2 N acts on the body in the direction of its motion for 5 s . The increase in the Kinetic energy of the body is _____ J

Question

A body of mass 5 kg is moving with a momentum of 10 kg m s - 1 . Now a force of 2 N acts on the body in the direction of its motion for 5 s . The increase in the Kinetic energy of the body is _____ J .

TestHub · Accepted Answer

The formula to calculate the change on momentum of the object is given by
$p_{f} - p_{i} = \int F d t . . . (1)$
Substitute the values of the known parameters into equation (1) and solve to calculate the final momentum of the object.
$\begin{array}{rcl} p_{f} - 10 kg m s^{- 1} & = & 2 N \times 5 s \\ \Rightarrow & p_{f} = (10 + 10) kg m s^{- 1} \\ = & 20 kg m s^{- 1} \end{array}$
The formula to calculate increase in kinetic energy $(∆ K)$ of the particle is given by
$∆ K = \frac{1}{2 m} ({p_{f}}^{2} - {p_{i}}^{2}) . . . (2)$
Substitute the values of the known parameters into equation (2) to calculate the required increase in kinetic energy.
$\begin{array}{rcl} ∆ K & = & \frac{1}{2 \times 5 kg} \times (20^{2} - 10^{2}) {kg}^{2} m^{2} s^{- 2} \\ = & 30 J \end{array}$

Physics - W.E.P. Question with Solution | TestHub

Doubts & Discussion