Using a horizontal force ` 200N`, we intend to move a wooden cabinet across a floor at constant velocity. What is the frictional force that will be exerted on the cabinet?

Explanation

To solve the problem, we need to determine the frictional force exerted on the wooden cabinet when a horizontal force of 200 N is applied to move it at a constant velocity.

### Step-by-Step Solution:

1. **Understanding the Situation**:
- We have a wooden cabinet that is being pushed with a horizontal force of 200 N.
- The cabinet is moving at a constant velocity across the floor.

2. **Applying Newton's First Law of Motion**:
- According to Newton's First Law, an object will remain at rest or in uniform motion unless acted upon by a net external force.
- Since the cabinet is moving at a constant velocity, the net force acting on it must be zero.

3. **Setting Up the Equation**:
- Let \( F \) be the applied force (200 N) and \( f \) be the frictional force.
- Since the net force is zero, we can write the equation:
\[ F - f = 0 \]

4. **Solving for the Frictional Force**:
- Rearranging the equation gives us:
\[ f = F \]
- Substituting the value of \( F \):
\[ f = 200 \, \text{N} \]

5. **Conclusion**:
- The frictional force exerted on the cabinet is 200 N.

### Final Answer:
The frictional force that will be exerted on the cabinet is **200 N**.