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Question:

A solid cylinder and a hollow cylinder, both of the same mass and same external diameter are released from the same height at the same time on an inclined plane. Both roll down without slipping. Which one will reach the bottom first?

Solid cylinder

Both together

Both together only when angle of inclination of plane is 45o

Hollow cylinder

Solution:

Time taken to reach the bottom of inclined plane = √(2l(1+K²/R²)/(g sin θ))
Here, l is length of incline plane
For solid cylinder K² = R²/2
For hollow cylinder K² = R²
Hence, solid cylinder will reach the bottom first.