Question

A body of mass 2 kg is moving with a velocity of 10 m/s. What is its kinetic energy?

• A. 100 J
• B. 200 J
• C. 50 J
• D. 400 J

Hint:

Kinetic energy depends on the square of the velocity, so doubling the speed quadruples the kinetic energy. Always check unit consistency.

Answer 1

The Correct Option is A

Step 1: Recall the formula for kinetic energy (\( KE \)) of a moving body: \[ KE = \frac{1}{2} m v^2, \] where \( m \) is the mass and \( v \) is the velocity.
Step 2: Substitute the given values: - Mass \( m = 2 \, \text{kg} \), - Velocity \( v = 10 \, \text{m/s} \). \[ KE = \frac{1}{2} \cdot 2 \cdot (10)^2. \]
Step 3: Perform the calculation step-by-step: - First, compute the square of the velocity: \[ (10)^2 = 100. \] - Then multiply by the mass and divide by 2: \[ KE = \frac{1}{2} \cdot 2 \cdot 100 = 1 \cdot 100 = 100 \, \text{J}. \]
Step 4: Verify the result.
The units are consistent (\( \text{kg} \cdot (\text{m/s})^2 = \text{J} \)), and the value 100 J matches the expected kinetic energy for the given mass and velocity.