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

- The energy required to throw the object is given by its initial kinetic energy: \[ E_{\text{kinetic}} = \frac{1}{2} m v^2 = \frac{1}{2} \times 3 \times (10)^2 = 150 \, \text{J} \]
- The potential energy at the maximum height is: \[ E_{\text{potential}} = mgh = 3 \times 10 \times 4.7 = 141 \, \text{J} \]
- The loss in energy due to air resistance is the difference between the initial energy and the potential energy at the maximum height: \[ \text{Loss in energy} = 150 \, \text{J} - 141 \, \text{J} = 9 \, \text{J} \]