Physics Chapt X O e webassign netweb/student/Assignment-Responsessubmit?dep 1602

Question

Physics Chapt X O e webassign netweb/student/Assignment-Responsessubmit?dep 16023719ea10 O -2.25 points cuto 6 P o35. A 54.5-kg skateboarder starts out with a speed of 1,75 m/s. He does +80.0 )of work on himself by pushing with his feet against the ground. In addition, friction does -265 J of work on him. In both cases, the forces doing the work are nonconservative. The final speed of the skateboarder is 6.05 m/s. (a) Calculate the change (APE-PEE PEo) in the gravitational potential energy. (b) How much has the vertical height of the skater changed? Is the skater above or below the starting point? O above the starting point O below the starting point Additional Materials Section 6.4. Submit Answer Save Progress CJ10 6 P.037, that are important in this problem. zero. Interactive Learningware 6.3 provides a review of the concepts the swing his speed is momentarily A gymnast is swinging on a high bar. The distance between his waist and the bar is 1.1 m, as the drawing shows, At top of the Ignoring friction and treating the gymnast as if all his mass is located at his waist, find his speed at the bottom of the swing.

Explanation / Answer

wnc = chaneg in kinetic energy+change in potential energy

change in potential energy = wnc-chaneg in kinetic enrgy

change in potential energy = 80-265-(1/2m(v2^2-v1^2) = 80-265-913.965 = -1098.965 J

change in potential energy = mg(h-h0)

h-h0 = -1098.965/54.5*9.8 = -2.06 m

below the starting point

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