Physics 163

Unit 5: Work, Energy and Power

Problem Set B

Problem 13:

Esteemed Chinese ski jumper, Li Ping Phar, leaves the jump ramp with a kinetic energy of 16046 Joules and a potential energy (relative to the bottom of the ski hill) of 12836 Joules. She encounters -2052 Joules of work due to air resistance during her flight through the air. Determine the speed (in m/s) of her 49.2-kg body the instant prior to striking the ground at the bottom of the hill.

• Read the problem carefully and diagram the physical situation
• Identify known and unknown information in an organized manner
• Take the time to plot out a strategy prior to beginning the solution
• Identify an appropriate formula to use
• Perform step-by-step algebraic manipulations

Use the equation below to solve this problem. Cancel terms, substitute and solve.

KEi + PEi + Wnc = KEf + PEf

Work and energy principles and mathematical relationships can be reviewed on the Set B Overview page.

Further information about the work and energy relationship is available online at The Physics Classroom.