A) Work that must be done to stop it is 1.3 * 10⁴J ; B) Required average power = - 650 W.
What is rotational energy?
Rotational energy is also known as angular kinetic energy and is defined as the kinetic energy due to the rotation of any object and is also part of the total kinetic energy.
Initial rotational energy kinetic energy is ;
Ki = 1/2 * I * ω²
= 1/2 *M*R²ω²
ω= (206rev/min) * (2πrad/1rev) * (1min/60s)
= 21.57 rad/sec
Ki= 1/2 *M*R²ω²
Given mass is 29 kg, and radius is 1.4m
= 1/2 * 29 * 1.4² * 21.57²
Ki = 1.3 * 10⁴ J
As hoop is brought to stop. Kf = 0 J
Required average power;
P = (Kf - Ki)/t
Given t = 20s
P= (0 - 1.3 * 10⁴)/20
Average power = - 650 W
To know more about rotational energy, refer
https://brainly.com/question/25803184
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