Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Work Power Energy

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 : 

Options:

4.4 J

2.8 J

2.6 J

3.8 J

Correct Answer:

4.4 J

Explanation:

Initial KE \( = \frac{p^2_1}{2m} = \frac{10*10}{2*5} = 10 \text{ J}\)

Impulse \( = p_2 - p_1 = F*t\)

\(\Rightarrow p_2 - 10 = 0.2 * 10\)

\(\Rightarrow p_2 = 12 \text{ kg m/s}\)

Final KE \( = \frac{p^2_2}{2m} = \frac{12*12}{2*5} = 14.4 \text{ J}\)

\(\Delta KE = 14.4 \text{ J} - 10 \text{ J} = 4.4 \text{ J}\)