A body of mass 5 kg is moving with a momentum of 10 kg-m/s. A force of 0.2 N acts on it in the direction of motion of the body for 10 seconds. The increase in its kinetic energy is

Question

A body of mass 5 kg is moving with a momentum of 10 kg-m/s. A force of 0.2 N acts on it in the direction of motion of the body for 10 seconds. The increase in its kinetic energy is (A) 2.8 joules (B) 3.2 joules (C) 3.8 joules (D) 4.4 joules

Tardigrade Admin · Accepted Answer

Change in momentum = Force × time P2 - P1 = F × t = 0.2 × 10 = 2 ⇒ P2=2 + P1 =2 + 10 =12 kg-m/s Increase in K.E. =(1/2m)(P22-P12) =(1/2×5)[(12)2-(10)2] =(44/10)=4.4 J

Q. A body of mass $5 k g$ is moving with a momentum of $10 k g - m / s .$ A force of $0.2 N$ acts on it in the direction of motion of the body for $10$ seconds. The increase in its kinetic energy is

2.8 joules

3.2 joules

3.8 joules

4.4 joules

Change in momentum = Force $\times$ time
$P_{2} - P_{1} = F \times t = 0.2 \times 10 = 2$
$\Rightarrow P_{2} = 2 + P_{1} = 2 + 10 = 12 k g - m / s$
Increase in $K . E .$
$= \frac{1}{2 m} (P_{2}^{2} - P_{1}^{2})$
$= \frac{1}{2 \times 5} [(12)^{2} - (10)^{2}]$
$= \frac{44}{10} = 4.4 J$

Q. A body of mass 5kg is moving with a momentum of 10kg−m/s. A force of 0.2N acts on it in the direction of motion of the body for 10 seconds. The increase in its kinetic energy is