Question

Height: 1.60 m Length of each arm: 0.60 m
Mass: 75 kg Mass of each leg: 12 kg
Length of each leg: 0.75 m Mass of each arm: 4 kg

Assume that the mass in the arms and legs is uniformly distributed.

How much initial kinetic energy is required for the athlete to clear a high jump bar set at 2 m?
(7 marks)

Answer 1

Answer:

To determine:(a)Calculate the average angular velocity of person’s arm and legs.(b)Calculate the amount of rotational kinetic energy in this person’s arms and legs as he walks(c)Calculate the total kinetic energy due to both his forward motion and his rotation.(d)What percentage of his kinetic energy is due to the rotation of his legs and arms?Answer:(a)The average angular velocity of person’s arm and legs is.(b)The amount of rotational kinetic energy in this person’s arms and legs as he walks is.(c)The total kinetic energy due to both his forward motion and his rotation is.(d)The percentage of his kinetic energy due to the rotation of his legs and arms is.Explanation:(a)Calculate the average angular velocity of person’s arm and legs.Therefore, the average angular velocity of person’s arm and legs is.(b)The expression for the moment of inertia of the arm and leg is as follows,Here,is the mass of the arm,is the mass of the leg,is the length of the leg and is the length of the arm.Calculate the moment of inertia of the arm and the leg.The expression for the rotational kinetic energy is as follows,Here,is the moment of the inertia and is the angular velocity.Calculate the rotational kinetic energy.Therefore, the amount of rotational kinetic energy in this person’s arms and legs as he walks is.(C)Calculate the translational kinetic energy.Here,is the mass and is the linear speed.Calculate the total kinetic energy due to the person’s forward motion and his rotation.Therefore, the total kinetic energy due to the person’s forward motion and his rotation is.(d)Calculate the percentage of his kinetic energy due to the rotation of his legs and arms.Therefore, the percentage of his kinetic energy due to the rotation of his legs and arm is.