Question

A baseball pitcher throws the ball in a motion where there is rotation of the forearm about the elbow joint as well as other movements. If the linear velocity of the ball relative to the elbow joint is m/s at a distance of m from the joint and the moment of inertia of the forearm is kg·m2, what is the rotational kinetic energy of the forearm?

Answer 1

Answer:

K = ½ kg m2 / s2

Explanation:

The kinetic energy rotation is given by the expression

    K = ½ I w²

Where I is the moment of inertia and w is the angular velocity.

We have a relationship between linear and angular velocity

    v = w r  

Where r  the distance from the point of rotation, in this case it is the point or where the ball is, so the linear velocity is the same as the ball.

      w = v / r

We replace

      K = ½ I (v / r)²

Let's calculate

      K = ½ kg m2 )(m/s )/ m) 2

      K = ½ kg m2 / s2