Question

ABC is a fixed incline plane with D mid point of AC. Part AD of incline plane is rough such that when a sphere released from A starts rolling, while the part DC is smooth. The sphere reaches the bottom point C, then –

• A. It is in pure rolling in the part DC
• B. Work done by friction on the sphere is negative when it moves from A to D
• C. Mechanical energy of sphere remains constant for its motion from A to C
• D. All of the above

Answer 1

Answer: (C)

Mechanical energy of sphere remains constant for its motion from A to C

Answer 2

As surface DC is smooth it will slip but as in path AD it is in pure rolling therefore work done by friction is zero. Hence mechanical energy is conserved.