Q: Before jumping in water from above a swimmer bends his body to
(a) Increase moment of inertia
(b) Decrease moment of inertia
(c) Decrease the angular momentum
(d) Reduce the angular velocity
Ans: (b)
Sol: As we have seen that before jumping in water from above a swimmer bends his body because by doing this his moment of Inertia decreases and hence angular velocity increases (L = I ω = constant ) . But on reaching the surface of water he stretches the body so that moment of inertia will increase and hence angular velocity will decrease . Hence he keeps his body safe by doing this .