# The Time-keeper

Classical Mechanics Level 5

A man sits on the inner side of a hollow sphere and counts the number of seconds as they pass. How many seconds would have passed by the time one oscillation is over?

Details and Assumptions

• Length of string is $$l=1 \text{ m}$$
• Radius of sphere is $$R=1 \text{ m}$$
• String is attached at point $$P$$ and man sits diametrically opposite to this point.
• Masses of both man and sphere are same.
• The man doesn't slip on the sphere ie., he sits at the same point on the sphere.

• Assume the figure at the bottom of the sphere to be the man.

• The oscillations take place in uniform gravitational field where $$g = 9.81$$ SI units.

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