NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Laws of Motion
NEET · Physics · Laws of Motion
Assertion : In the system of two blocks of equal masses as shown,...
Assertion : In the system of two blocks of equal masses as shown, the coefficient of friction between the blocks ((\mu_2)) is less than coefficient of friction ((\mu_1)) between lower block and ground.
For all values of force applied on upper block lower block remains at rest.
Reason : Frictional force on lower block due to upper block is not sufficient to overcome the frictional force on lower block due to ground.
Options
- AIf both Assertion and Reason are correct and Reason is the correct explanation of Assertion
- BIf both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- CIf Assertion is true but Reason is false
- DIf Assertion is false but Reason is true
Correct answer
A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion
Step-by-step solution
Why assertion is true
- For two equal-mass blocks, the maximum static friction at the ground is (\mu 1(2 \mathrm{mg})), which exceeds any friction demand transmitted from the top block because (\mu 2 < \mu 1) limits the interface force first. Hence, the lower block can remain at rest for all applied F.
Why reason is correct
- The friction exerted by the upper block on the lower is bounded by (\mu 2 \mathrm{mg}), which is smaller than the maximum ground friction (\mu 1(2 \mathrm{mg})); therefore, this interface force can't overcome ground friction, keeping the lower block stationary.