A steel playground slide is 525 m long and is raised 275 m o

A steel playground slide is 5.25 m long and is raised 2.75 m on one end. A 45.0 kg child slides down from the top starting at rest. The final speed of the child at the bottom is 6.81 m/s. Find the average force of friction between the child and the slide.

Solution

Height of slide= 2.75 m

Length of slide = 5.25 m

Inital potential energy = mgh = 45*9.8*2.75 = 1212.75 J

Final potential energy = 0

Intial kinetic energy =0

Final kinetic energy = 1/2 mV^2 = 1/2*45*6.81*6.81 = 1043.46

work done by force = 169.29

Force = work done/distance = 169.29/5.25 = 32.24 N