A25 kg bear slides, from rest, 12 m down a lodgepole pine tree, moving with a speed of 5.6 m/s just before hitting the ground.
(a) what change occurs in the gravitational potential energy of the bear – earth system during the slide?
(b) what is the kinetic energy of the bear just before hitting the ground?
(c) what is the average frictional force that acts on the sliding bear?

(A) -2940 J

(B) 392 J

(C) 212.33 N

Explanation:

mass of bear (m) = 25 kg

height of the pole (h) = 12 m

speed (v) = 5.6 m/s

acceleration due to gravity (g) = 9.8 m/s

(A) change in gravitational potential energy (ΔU) = mg(height at the bottom- height at the top)

height at the bottom = 0

         = 25 x 9.8 x (0-12) = -2940 J

(B) kinetic energy of the Bear (KE) =

           =  = 392 J

(C) average frictional force =

 \frac{-(ΔKE+ΔU)}{h}[/tex] =

=   = 212.33 N

iron would move it is magnetic there is a mag field around the current in the wire