Question

The power exerted by a muscle is the product of the force exerted and the velocity of contraction. The area of which of these shaded regions represents the power exerted while a weight is lifted at maximum speed ?

1. Latifah

The power exerted by a muscle is the product of the force exerted and the velocity of contraction. The area of which of these shaded regions represents the power exerted while a weight is lifted at maximum speed is given below

Explanation:

The work done to accelerate a sprinter and increase her/his kinetic energy comes mainly from the compression and extension of muscle fibers and tendons, which act like springs.

The work done by a muscle in a contraction is the product of the force it exerts and the distance it shortens.

The amount of force a muscle can apply for a given contraction depends on the speed of contraction; the slower the contraction the greater the force.

Film of a male sprinter (mass = 70 kg) showed that he accelerated from rest to 3.0 m/s in his first step, to 4.2 m/s in his second step (while his other foot was on the ground) and to 5.0 m/s in the third step.

Each change in kinetic energy came from work done by his muscles. The change decreases slightly for each step because there is less time between steps and this decreases the amount of work his muscles can do for the same contraction. Thus the increase of energy cannot go on forever! The work done by the muscles while the sprinter is moving with constant speed is serving to make up for various energy losses: friction in the joints, air resistance, and heat losses in the tendons as they stretch and recoil.