Championship swimmers take about 22 s and about 30 arm strokes to move through the water in a 50 m freestyle race.The swimmer's
metabolic power is 800 W . A) If the efficiency for swimming is 25 %, how much energy is expended moving through the water in a 50 m race? B) If half the energy is used in arm motion and half in leg motion, what is the energy expenditure per arm stroke? C)Model the swimmer's hand as a paddle. During one arm stroke, the paddle moves halfway around a 90 cm-radius circle. If all the swimmer's forward propulsion during an arm stroke comes from the hand pushing on the water and none from the arm (somewhat of an oversimplification), what is the average force of the hand on the water?
The moment of a given force about a given axis of rotation can be decreased by decreasing the perpendicular distance of force from the axis of rotation.
Newton's second law says that the acceleration of an object is produced by the force exerted on it. Having this in mind, if you hit a baseball with a bat it will <u>accelerate according to the applied force.</u>