Question

If no external force acts on system,

• A. Velocity of centre of mass remains constant.
• B. Position of centre of mass remains constant.
• C. Acceleration of centre of mass remains non-zero and constant.
• D. All of the above.

Answer 1

Answer: (A)

Velocity of centre of mass remains constant.

$F_{ext}=\frac{dp}{dt}$

Since $F_{ext}=0$

$\Rightarrow \frac{dp}{dt}=0$

$\therefore p=constant$