LUS cutnell, hysics, 10e GENERAL PHYSICS (PHYS 2001/e Chepter 0%, Problem 3s you
ID: 1580958 • Letter: L
Question
LUS cutnell, hysics, 10e GENERAL PHYSICS (PHYS 2001/e Chepter 0%, Problem 3s your answer is partial, oorrect. Try again. A51.3.kg skateboander starts out with a speed of 1.60 m/s. He does 97.8 3 of work on himself by pushing with his feet againut the ground inadation, ctin does-2233 f work on him.In both cases, the farces doing the work ane non-conservative The final speed of the skateboarder is 8.45 m's. (a) Calculate the change (P- PEal) in the gravitational potertial energy. (b) Haw much has the vertical height of the skater changed Give te absolte value (b) Number o e FIND PAPERWORExplanation / Answer
a)
The kinetic energy change is
K = 1/2 m (vf^2 - v1^2)
K = 1/2 x 51.3 x (8.45^2 - 1.60^2)
K = 1765.8 J
According to the kinetic energy theorem, K equals the work done bay all the forces acting on the system.
Therefore
K = 89.8 - 219 - (PE)
(PE) = 97.8 - 223 - 1765.8 = -1891 J
b)
The height change is
h = (PE) / mg
h = 1891 / (51.3 x 9.81)
h = 3.758 m
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