A person has a box of weight 20 kg. The energy of the box when be keeps the box in his hand for 5 minutes is

Options

A. 100 J
B. 200 J
C. 60000 J
D. zero

Explanation

To solve the question, we need to understand the concept of work done and energy in the context of the box being held by a person.

### Step-by-Step Solution:

1. **Identify the Weight of the Box**: The weight of the box is given as 20 kg.

2. **Understand the Force Acting on the Box**: The force acting on the box due to gravity can be calculated using the formula:
\[ \text{Weight} = \text{mass} \times \text{gravity} \]
Here, the acceleration due to gravity (g) is approximately \(9.8 \, \text{m/s}^2\). Therefore, the weight (force) of the box is:
\[ \text{Weight} = 20 \, \text{kg} \times 9.8 \, \text{m/s}^2 = 196 \, \text{N} \]

3. **Consider the Displacement**: The person is holding the box in a stationary position for 5 minutes. Since the box is not moving (displacement is zero), we conclude that the displacement (d) is 0 meters.

4. **Calculate Work Done**: Work done (W) is defined as:
\[ W = \text{Force} \times \text{Displacement} \times \cos(\theta) \]
In this case, since the box is not moving, the displacement is 0. Therefore:
\[ W = 196 \, \text{N} \times 0 \, \text{m} \times \cos(0) = 0 \, \text{J} \]

5. **Determine the Energy of the Box**: Since the work done is 0, it implies that there is no change in energy of the box when it is held stationary. Thus, the energy of the box is:
\[ \text{Energy} = 0 \, \text{J} \]

6. **Final Answer**: The energy of the box when the person keeps it in his hand for 5 minutes is 0 joules.