A vehicle is moving on a rough road in a straight line with uniform velocity. Then

Options

A. no force is acting on the vehicle
B. a force must act on the vehicle
C. an acceleration is being produced in the vehicle
D. no work is being done on the vehicle

Explanation

To solve the question regarding the vehicle moving on a rough road with uniform velocity, let's break it down step by step.

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- A vehicle is moving on a rough road in a straight line with uniform velocity. This means that the speed of the vehicle is constant and there is no change in direction.

2. **Identifying Forces Acting on the Vehicle**:
- Since the road is rough, there will be a frictional force acting on the vehicle in the opposite direction of its motion. This frictional force opposes the motion of the vehicle.

3. **Analyzing the Condition of Uniform Velocity**:
- For an object to move with uniform velocity, the net force acting on it must be zero. This means that all the forces acting on the vehicle must balance out.

4. **Applying Newton's First Law**:
- According to Newton's first law of motion, an object will remain at rest or move in a straight line at constant speed unless acted upon by a net external force. In this case, since the vehicle is moving with uniform velocity, the net force must be zero.

5. **Balancing Forces**:
- The frictional force acting on the vehicle must be balanced by an external force applied in the direction of motion. If the frictional force is F_friction, then an external force F_external must be applied such that:
\[ F_{external} = F_{friction} \]
- This balance of forces results in a net force of zero, allowing the vehicle to maintain its uniform velocity.

6. **Conclusion**:
- Since an external force must be acting on the vehicle to counteract the frictional force for it to maintain uniform velocity, we can conclude that:
- **A force must act on the vehicle** to keep it moving at a constant speed despite the friction.

### Answer:
The correct answer to the question is: **A force must act on the vehicle.**