NEET
- Exam
- NEET
- Subject
- Physics
- Chapter
- Laws of Motion
NEET · Physics · Laws of Motion
Assertion : A body of mass 10 kg is placed on a rough inclined...
Assertion : A body of mass 10 kg is placed on a rough inclined surface ((\mu=07)). The surface is inclined to horizontal at angle (30^{\circ}). Acceleration of the body down the plane will be zero.
Reason : Work done by friction is always negative.
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
C. If Assertion is true but Reason is false
Step-by-step solution
Quick justification: the weight component down the plane (49 N) is less than maximum friction ((\approx 59.4 \mathrm{~N})), so the body doesn't move (\rightarrow) acceleration (Assertion true). The Reason is false because friction's work isn't always negative - the sign depends on the direction of displacement relative to the friction force (static friction can even do positive work in some cases).