Question

A body of mass 4 kg is moving with a velocity of 3 m/s. What is its kinetic energy?

• A. 18 J
• B. 36 J
• C. 9 J
• D. 12 J

Hint:

Use the kinetic energy formula \( KE = \frac{1}{2} m v^2 \) and ensure units are consistent (mass in kg, velocity in m/s) to find the energy in joules.

Answer 1

The Correct Option is A

Given: \[ m = 4 \, \text{kg}, \quad v = 3 \, \text{m/s} \] Step 1: Formula for Kinetic Energy
The kinetic energy \( KE \) of a body is given by: \[ KE = \frac{1}{2} m v^2 \] Step 2: Substitute the Values
Substitute the given values into the formula: \[ KE = \frac{1}{2} \cdot 4 \cdot (3)^2 = \frac{1}{2} \cdot 4 \cdot 9 = 2 \cdot 9 = 18 \, \text{J} \] Thus, the kinetic energy is: \[ \boxed{18 \, \text{J}} \]