Answer to Question #154373 in Classical Mechanics for John smith

Question

5. Explain the law of conservation of mass affects the kinetic and gravitational potentia energy of a downhill skier at the top, middle and bottom of a hill. 

Answer 1

Answer

Downhill skiing is a classic example of the relationship between work and energy on body.

The skier begins at an elevated position, thus there is a large quantity of potential energy.If starting from rest, the mechanical energy of the skier is entirely in the form of potential energy.

Now As the skier begins down the hill, potential energy decreases and kinetic energy is gained.

Now As the skier loses height she gains speed. Once the skier reaches the bottom of the hill, her height reaches at zero as potential energy.

At this point, her speed and kinetic energy have reached a maximum.

This energy state is maintained until the skier meets a section of unpacked snow and skids to a stop due to the force of friction.

The friction force, sometimes known as a dissipative force, does work upon the skier in order to decrease her total mechanical energy.

Thus, as the force of friction acts over an increasing distance, the quantity of work increases and the mechanical energy of the skier is gradually dissipated. Ultimately, the skier runs out of energy and comes to a rest position. Work done by an external force (friction) has served to change the total mechanical energy of the skier.

Therefore at all point top, middle and bottom of a hill total energy is conserved.