Question

A 60 kg gymnast leaves the floor to perform a somersault, with a reactive force of 2760 N. The center of gravity is 22 cm perpendicular from the line of action of the force.

As she first leaves the floor, she can be modelled as a long cylinder with moment of inertia md^2/12

(where d is her length, 1.60 m). The time it takes her to leave the floor is 55 ms.

As she leaves the floor calculate:

1. Torque (in N m)

2. Moment of inertia (in kg m²)

3. Angular acceleration (in rad s^-2)

4. Angular velocity (in rad s^-1)

5. Angular momentum (kg m² s^-1)

After leaving the floor a dancer tucks, with a radius of 55 cm. She can now be modelled as a sphere with moment of inertia ​(2mr^2)/5. State or calculate her new:

1. Angular momentum (in kg m2 s-1).

2. Moment of inertia (in kg m2).

3. Angular velocity (in rad s-1).

Answer 1