A body of mass 2 kg is placed in a rough surface. When a force of 60 N is applied on it, it starts moving with an acceleration of `15m//s^2`. Find the friction force acting on it.

Options

A. 10N
B. 20N
C. 30N
D. 40N

Answer

To solve the problem step by step, we will use Newton's second law of motion and the concept of net force.

### Step-by-Step Solution:

1. **Identify the Given Values:**
- Mass of the body (m) = 2 kg
- Applied force (F_applied) = 60 N
- Acceleration (a) = 15 m/s²

2. **Write the Formula for Net Force:**
According to Newton's second law, the net force acting on an object is given by:
\[ F_{net} = m \cdot a \]

3. **Calculate the Net Force:**
Substitute the values of mass and acceleration into the formula:
\[ F_{net} = 2 \, \text{kg} \cdot 15 \, \text{m/s}^2 = 30 \, \text{N} \]

4. **Understand the Forces Acting on the Body:**
The applied force is acting in the forward direction, while the frictional force (F_friction) opposes the motion. Therefore, we can express the net force as:
\[ F_{net} = F_{applied} - F_{friction} \]

5. **Set Up the Equation:**
We can substitute the known values into the net force equation:
\[ 30 \, \text{N} = 60 \, \text{N} - F_{friction} \]

6. **Solve for the Frictional Force:**
Rearranging the equation to find the frictional force:
\[ F_{friction} = 60 \, \text{N} - 30 \, \text{N} = 30 \, \text{N} \]

7. **Conclusion:**
The frictional force acting on the body is:
\[ F_{friction} = 30 \, \text{N} \]

### Final Answer:
The frictional force acting on the body is **30 N**.

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