A 61.0 kg skier is at the top of a slope, as shown in the figure. At the initial

Question

A 61.0 kg skier is at the top of a slope, as shown in the figure. At the initial point , she is 8.0 m vertically above point .

(a) Setting the zero level for gravitational potential energy at (b), find the gravitational potential energy of this system when the skier is at (a) and then at (b) . Finally, find the change in potential energy of the skier-Earth system as the skier goes from point to point .

PEi = J

PEf = J

deltaPE = J

(b) Repeat this problem with the zero-level at point .

PEi = J

PEf = J

deltaPE = J

(c) Repeat again, with the zero level 2.00 m higher than point .

PEi = J

PEf = J

deltaPE = J

Explanation / Answer

a)
PEf = 0 J assumption of question
PEi = mgh = 61 * 9.8 * 8 = 4782.4 J

deltaPE =PEf- PEi= -4782.4 J

b) zero lavel at point b

PEi = 0 J assumption of question
PEf = mgh = 61* 9.8 * (-8) = -4782.4 J (we are taking -8 since gravity and change in position in same direction)

deltaPE =PEf- PEi= -4782.4 J

c) zero level 2.00 m higher than point a

PEi = mgh = 61 * 9.8 * (8-2) = 3586.8 J

PEf = mgh = 61* 9.8* (-2) = -1195.6 J

deltaPE =PEf- PEi= -4782.4 J

d) zero level 2.00 m higher than point b

PEi = mgh = 61 * 9.8 * (-2) = -1195.6 J

PEf = mgh = 61* 9.8* -(8+2) = 5978 J

deltaPE =PEf- PEi= -4782.4 J

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