A body of mass 40 gm is moving with a constant velocity of `2cm//sec` on a horizontal frictionless table. The force on the table is

Options

A. 39200 dyne
B. 160 dyne
C. 80 dyne
D. Zero dyne

Answer

To solve the problem, we need to determine the force exerted by the body on the table. The key points to consider are the mass of the body, the acceleration due to gravity, and the relationship between the weight of the body and the normal force exerted by the table.

### Step-by-Step Solution:

1. **Identify the mass of the body**:
The mass of the body is given as 40 grams (gm).

2. **Convert mass to kilograms (if necessary)**:
Although we can work in grams, it’s often useful to convert to kilograms for standard units.
\[ 40 \, \text{gm} = 0.04 \, \text{kg} \]

3. **Calculate the weight of the body**:
The weight (W) of the body can be calculated using the formula:
\[ W = m \cdot g \]
where \( m \) is the mass and \( g \) is the acceleration due to gravity. In this case, we will use \( g = 980 \, \text{cm/s}^2 \) since the mass is given in grams.
\[ W = 40 \, \text{gm} \cdot 980 \, \text{cm/s}^2 \]

4. **Perform the multiplication**:
\[ W = 40 \cdot 980 = 39200 \, \text{gm} \cdot \text{cm/s}^2 \]

5. **Convert the weight to dynes**:
In the CGS system, 1 gm·cm/s² is equal to 1 dyne. Therefore, the weight in dynes is:
\[ W = 39200 \, \text{dynes} \]

6. **Conclusion**:
The force exerted by the body on the table (which is equal to the weight of the body) is:
\[ \text{Force on the table} = 39200 \, \text{dynes} \]

### Final Answer:
The force on the table is **39200 dynes**.

---