Energy associated with forces that depend on the position or configuration of a body Objects acquire potential energy when work is done on it As an object loses potential energy it can do work Potential energy is the capacity to do work even if not doing work yet ID: 1021470
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1. Potential Energy
2. Potential EnergyEnergy associated with forces that depend on the position or configuration of a bodyObjects acquire potential energy when work is done on itAs an object loses potential energy, it can do work
3. Potential energy is the capacity to do work even if not doing work yetPotential energy can be stored for later useEqual to the negative of the work done on it to give it this potential energy to begin with
4. Gravitational Potential EnergyPotential energy because of an object’s position relative to the EarthW = FdcosθTo give an object PE it must be worked on as it is lifted to a height (h)The force to lift it is equal to the force of gravity on it (mg)W = mgh
5. Gravitational Potential EnergyPEG = mgh h- height above referenceWG = -mgh2 – mgh1 = ΔPEThe initial reference point doesn’t matter, it is the change in PE that matters
6. Example 1A 1000kg roller coaster car moves from pt 1 to 2 and then to 3. A) what is the PE at 2 and 3 relative to 1? B) What is the ΔPE when it goes from 2 to 3? C) Repeat part A and B relative to point 3.
7. Problem How much work does a bricklayer do to carry 30.2 kg of bricks from the ground up to the third floor (height = 11.1 m) of a building under construction? What is the gravitational potential energy of the brick-Earth system when the bricklayer reaches the third floor?