el work-energy theorem equation with what does the box reach the bottom roller c

Question

el work-energy theorem equation with what does the box reach the bottom roller coaster al an amusement park is at rest an top of a 30m bill (point A). The ear stans to roll down the hill and reaches point B, which is 10m above the ground. and then rolls up the track to point C, which is 20 m above the ground a. A student assumes no energy is lost, and solves for how fast is the car moving point C using energy arguments. What will be the answer that he gets? measured to be 2m/s, Describe what percentage lf the final speed at C is actual energy was "lost "and where did it go.

Explanation / Answer

5.a)

conserve energy

KE = PE

0.5mv^2 + mgh= mgH

0.5v^2 = 9.81(30-20)

v = 14.00 m/s

b.)energy lost = total enegy at A- total enegy at C

E1 = mgH - mgh-0.5mv^2

E =m(30-20) - 0.5m*2*2

E1 = 96.1m

E =mgH = m*9.81*30 = 294.3m

so percentage of energy lost = (96.1m/294.3m)100 = 32.65%

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