Question

A body of mass 3 kg is thrown vertically upward from the ground with a velocity of \( 10 \, \text{ms}^{-1} \). If the maximum height reached by the body is 4.7 m, then the loss of energy due to air resistance is:

• A. 9 J
• B. 18 J
• C. 30 J
• D. 47 J

Hint:

When a body is projected vertically upward, the energy lost to air resistance can be calculated by finding the difference between the initial kinetic energy and the potential energy at the highest point.

Answer 1

The Correct Option is A

Step 1: Use energy conservation with loss

Initial kinetic energy = gain in potential energy + loss due to air resistance

\frac{1}{2}mv^2 = mgh + E_{loss}

Step 2: Substitute values

\frac{1}{2} \times 3 \times 10^2 = 3 \times 10 \times 4.7 + E_{loss}

150 = 141 + E_{loss}

Step 3: Solve

E_{loss} = 9 \, \text{J}

Final Answer: 9 \, \text{J}