Exams › NEET › Physics

The upper half of an inclined plane of inclination θ is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom, if the coefficient of friction between the block and lower half of the plane is given by

1. μ = 2/tanθ
2. μ = 2tanθ
3. μ = tanθ
4. μ = 1/tanθ

Correct answer: μ = 2tanθ

Solution

The block gains kinetic energy while sliding down the smooth upper half due to gravity. On the rough lower half, friction dissipates this energy. For the block to stop at the bottom, the work done by friction must equal the kinetic energy gained. This leads to μ = 2tanθ.

Related NEET Physics questions

• Conservation of momentum in a collision between particles can be understood from
• Assertion (A): According to Newton's third law sum of action and reaction is not equal to zero Reason (R) : The forces action and reaction acts on different bodies.
• Who proposed the concept of Inertia?
• Which of the following Newton's law(s) is/are not applicable in non-inertial reference frame.
• Assertion When a bus starts suddenly, a person standing in it falls backwards. Reason It is due to inertia of rest.
• A body of mass M hits normally a rigid wall with velocity V and bounces back with the same velocity. The impulse experienced by the body is:

⚔️ Practice NEET Physics free + battle 1v1 →