Determine the Gravitational potential energy

[Nicholasw]

Question

A Skier with a mass of 65.0 kg. Including equipment, starts from rest and accelerates down a slope. The slope is 27.0 m higher at the top than the bottom. The work done on the skier by the kinetic friction is 1.20 x 10^4 J.

How would I determine the Gravitational potential energy at the top slope relative too the bottom?

Kinetic energy at the bottom?

And the skiers speed at the bottom of the slope?

 

[jmcgraw]

The potential energy would just be mgh, with h = 27m.

Then to find the kinetic energy at the bottom you would subtract the energy lost to friction from the potential energy.

Once you have the kinetic energy, use (1/2)mv^2 = k, then solve for v to find the velocity.

 

[kp]

P.E. = mgh (65kg)(9.81)(27m) = 17.22 kJ

(P.E.)17.22kJ - (fs)12.0kJ = 1/2mv^2

5.22kJ = 1/2mv^2 (K.E. bottom)