Question

When the total external force acting on a moving system is zero, the velocity of the center of mass

• A. remains constant
• B. becomes zero
• C. increases
• D. becomes infinity
• E. decreases

Hint:

Internal forces cannot change the velocity of the center of mass of a system.

Answer 1

The Correct Option is A

Step 1: Concept
Newton's Second Law for a system of particles states $F_{ext} = M a_{cm}$.

Step 2: Meaning
Acceleration of the center of mass ($a_{cm}$) is the rate of change of the velocity of the center of mass ($v_{cm}$).

Step 3: Analysis
If $F_{ext} = 0$, then $a_{cm} = 0$. When acceleration is zero, the velocity does not change.

Step 4: Conclusion
Hence, the velocity of the center of mass remains constant.
Final Answer: (A)