If net external force acting on the system is zero then

Options

A. Velocity of the individual particle of the system will remain constant
B. Velocity of the center of mass of the system will remain constant
C. Velocity of the center of mass of the system will be zero
D. Velocity of the individual particle of the system will be zero

Answer

To solve the question, we need to analyze the implications of having a net external force of zero acting on a system. Here’s a step-by-step breakdown of the reasoning:

### Step 1: Understand the concept of net external force
The net external force acting on a system is the vector sum of all external forces acting on that system. If this force is zero, it indicates that there are no unbalanced forces acting on the system.

**Hint:** Remember that forces can be balanced, leading to a net force of zero.

### Step 2: Apply Newton's First Law of Motion
According to Newton's First Law of Motion, an object at rest will remain at rest, and an object in motion will continue in motion with a constant velocity unless acted upon by a net external force.

**Hint:** Think about how motion is affected when forces are balanced.

### Step 3: Analyze the momentum of the system
If the net external force is zero, the total momentum of the system remains constant. This is a direct consequence of Newton's Second Law, which states that the rate of change of momentum is equal to the net external force acting on an object.

**Hint:** Consider how momentum is defined and how it relates to velocity.

### Step 4: Relate momentum to the center of mass
The momentum of a system of particles can be expressed in terms of the center of mass. If the total momentum is constant and there are no external forces acting on the system, the center of mass of the system will also move with a constant velocity.

**Hint:** Recall the definition of the center of mass and its relationship with the total momentum of the system.

### Step 5: Conclusion
Since the net external force is zero, the velocity of the center of mass of the system will remain constant.

Thus, the correct answer to the question is that the velocity of the center of mass of the system will remain constant.

**Final Answer:** The velocity of the center of mass of the system will remain constant.