Question

The centre of mass of a system of particles does NOT depend on

• A. masses of the particles.
• B. internal forces on the particles.
• C. position of the particles.
• D. relative distance between the particles.

Hint:

Centre of mass: - Depends only on mass and position - Independent of forces (internal or external)

Answer 1

The Correct Option is B

Concept: Centre of mass (COM) depends only on mass distribution and positions: \[ \vec{R} = \frac{\sum m_i \vec{r}_i}{\sum m_i} \]

Step 1: Observe variables in formula.
COM depends on:
• masses ($m_i$)
• positions ($\vec{r}_i$)

Step 2: Analyze options.

• (A) Mass $\rightarrow$ affects COM $\Rightarrow$ depends
• (C) Position $\rightarrow$ affects COM $\Rightarrow$ depends
• (D) Relative distance $\rightarrow$ affects positions $\Rightarrow$ depends
• (B) Internal forces $\rightarrow$ do NOT appear in formula

Step 3: Conclusion.
\[ \text{COM does NOT depend on internal forces} \]