NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Center of Mass, Momentum and Collision
NEET · Physics · Center of Mass, Momentum and Collision
Given below are two statements: One is labelled as Assertion (A)...
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Two blocks of masses & are at rest. They are now moving towards each other under a mutual internal force. The velocity of centre of mass is zero.
Reason (R) : If no external force acts on the system, then velocity of centre of mass remains unchanged but can never be zero.
In the light of the above statements, choose the most appropriate answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A).
- BBoth (A) and (R) are true and (R) is NOT the correct explanation of (A).
- C(A) is true but (R) is false.
- D(A) is false but (R) is true.
Correct answer
C. (A) is true but (R) is false.
Step-by-step solution
Acceleration of centre of mass (\overrightarrow{\mathrm{a}}_{\mathrm{cm}}=\frac{\overrightarrow{\mathrm{F}}_{\mathrm{ext}}}{\mathrm{M}}) If no external force acts on the system (\overrightarrow{\mathrm{a}}_{\mathrm{cm}}=0) (Assertion is correct)
Reason is false because; (\overrightarrow{\mathrm{a}}_{\mathrm{cm}}=0) implies velocity will not change, if C.O.M is initially at rest, then it will remain at rest in absence of external force.