Mechanics: Work and Energy
Work and Energy: Audio Guided Solution
Extra Problem 13:
Esteemed Chinese ski jumper, Li Ping Phar, leaves the jump ramp with a kinetic energy of 16882 Joules and a potential energy (relative to the bottom of the ski hill) of 13505 Joules. She encounters -2094 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.
Audio Guided Solution
Use the equation below to solve this problem. Cancel terms, substitute and solve.
KEi + PEi + Wnc = KEf + PEf
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Habits of an Effective Problem Solver
An effective problem solver by habit approaches a physics problem in a manner that reflects a collection of disciplined habits. An effective problem-solver...
- ...reads the problem carefully and develops a mental picture of the physical situation. If needed, they sketch a simple diagram of the physical situation to help visualize it.
- ...identifies the known and unknown quantities in an organized manner, often times recording them on the diagram iteself. They equate given values to the symbols used to represent the corresponding quantity (e.g., vo = 0 m/s; a = 4.2 m/s/s; vf = 22.9 m/s; d = ???).
- ...plots a strategy for solving for the unknown quantity; the strategy will typically center around the use of physics equations be heavily dependent upon an understaning of physics principles.
- ...identifies the appropriate formula(s) to use, often times writing them down. Where needed, they perform the needed conversion of quantities into the proper unit.
- ...performs substitutions and algebraic manipulations in order to solve for the unknown quantity.