Mechanics: Work and Energy
Work and Energy: Audio Guided Solution
Extra Problem 9:
Tarzan and Jane, whose total mass is 116-kg, start their swing on a vine 17.7 m long such that the vine is initially at an angle of 30 degrees with the horizontal. At the bottom of the arc, Jane, whose mass is 46.4-kg, steps off. What is the maximum height (in m, relative to the lowest point of the arc) of the tree branch that Tarzan can land on as his swing continues?
Audio Guided Solution
Use the equations below to solve this problem. Cancel terms, substitute and solve.
KEi + PEi + Wnc = KEf + PEf
0.5•m•vi2 + m•g•h i + 0.5•k•xi2 + F•d•cos Θ = 0.5•m•vf2 + m•g•h f + 0.5•k•xf2
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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.