Physics
posted by Willy .
A sled rests at the top of a 25 degree slope that is 80m in length. If uk = .25 and the velocity at the bottom of the incline is 20m/s then what is the weight of the sled?

Potential energy loss going down = M*g*80 sin 25 = 331.3 M
Kinetic energy acquired going down = (1/2) M*(Vfinal)^2 = 200.0 M
Work done against friction going down =
M*g*cos25*80*uk = 177.6 M
The first number must equal the sum of the last two numbers. There is no value of mass M that works.