A particle is in straight line motion with uniform velocity A force is not required

Options

A. To increase the speed
B. To decrease the speed
C. To keep the same speed
D. To change the direction

Explanation

To solve the question regarding a particle in straight line motion with uniform velocity and whether a force is required, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding Uniform Velocity**:
- A particle is said to be in uniform motion when it travels equal distances in equal intervals of time, regardless of the length of the time intervals. This means that the velocity of the particle remains constant.

**Hint**: Recall the definition of uniform velocity and how it relates to distance and time.

2. **Acceleration and Force**:
- According to Newton's second law of motion, force is related to acceleration by the equation \( F = m \cdot a \), where \( F \) is the force, \( m \) is the mass of the object, and \( a \) is the acceleration.
- If the particle is moving with uniform velocity, its acceleration \( a \) is zero (since there is no change in velocity).

**Hint**: Remember that acceleration is the change in velocity over time. If velocity is constant, acceleration is zero.

3. **Implication of Zero Acceleration**:
- Since the acceleration is zero, we can substitute this into the equation for force:
\[ F = m \cdot 0 = 0 \]
- This indicates that no net force is acting on the particle when it is in uniform motion.

**Hint**: Consider what happens when acceleration is zero in the context of Newton's second law.

4. **Conclusion**:
- Therefore, a force is not required to maintain the uniform velocity of the particle. The particle will continue to move with the same velocity unless acted upon by an external force (as per Newton's first law of motion).

**Hint**: Reflect on Newton's first law, which states that an object in motion stays in motion unless acted upon by a net external force.

5. **Final Answer**:
- The answer to the question is that **a force is not required to keep the speed the same** (i.e., to maintain uniform velocity).

### Summary:
In summary, a particle moving with uniform velocity does not require any force to maintain that motion, as there is no change in its speed or direction. The only time a force would be necessary is if we wanted to change the speed or direction of the particle.