Question

A water-skier is being pulled by a tow rope attached to a boat. As the driver pushes the throttle forward, the skier accelerates. A 62.8-kg water-skier has an initial speed of 5.2 m/s. Later, the speed increases to 11.3 m/s. Determine the work done by the net external force acting on the skier.

Answer 1

3160.41J

Step-by-step explanation:

From the work energy theorem, the net work done is given by;

W = Kef - Keo

Where kef is final kinetic energy and keo is initial kinetic energy.

Now, from the question,

m = 62.8 kg

Initial speed(vo) = 5.2 m/s

Final speed (vf) = 11.3 m/s

We know that formula for kinetic energy is K = (1/2)mv²

Thus, Kef = (1/2)mvf² and Keo = (1/2)mvo²

Thus;

W = (1/2)mvf² - (1/2)mvo²

W = (m/2)(vf² - vo²)

W = (62.8/2)(11.3²-5.2²)

= 31.4(100.65) = 3160.41J