A mass of 10 kg is at a point A on a table. It is moved to a point B. If the line joining A and B is horizontal, what is the work done on the object by the gravitational force ? Explain your answer.

Explanation

To find the work done on the object by the gravitational force when it is moved horizontally from point A to point B, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Forces Acting on the Object**:
The gravitational force acting on the object is given by the weight of the object, which can be calculated using the formula:
\[ F_g = m \cdot g \]
where \( m = 10 \, \text{kg} \) and \( g \approx 9.81 \, \text{m/s}^2 \).

2. **Calculate the Gravitational Force**:
\[ F_g = 10 \, \text{kg} \cdot 9.81 \, \text{m/s}^2 = 98.1 \, \text{N} \]
This force acts downward.

3. **Determine the Displacement**:
The object is moved horizontally from point A to point B. Therefore, the displacement vector \( \vec{d} \) is horizontal.

4. **Find the Angle Between the Force and Displacement**:
The angle \( \theta \) between the gravitational force (which acts downward) and the displacement (which is horizontal) is \( 90^\circ \).

5. **Use the Work Formula**:
The work done \( W \) by a force is given by the formula:
\[ W = F \cdot d \cdot \cos(\theta) \]
In this case, since \( \theta = 90^\circ \):
\[ \cos(90^\circ) = 0 \]

6. **Calculate the Work Done**:
Substituting the values into the work formula:
\[ W = F_g \cdot d \cdot \cos(90^\circ) = 98.1 \, \text{N} \cdot d \cdot 0 = 0 \]
Therefore, the work done by the gravitational force when moving the object horizontally is:
\[ W = 0 \, \text{J} \]

### Conclusion:
The work done on the object by the gravitational force while moving it horizontally from point A to point B is **0 Joules**.