GPE into KE Tutorial
- An object's GPE may be transformed (converted) into KE. For example, a book falls off a table.
- Imagine all the GPE has been converted to KE; GPE = KE.
In our example just at the moment the book hits the floor all the GPE has been transformed into KE.
- We will assume all the GPE is converted into KE. There are no friction losses, wind resistance, etc.
- Knowing that KE = ½ m v2, the velocity can be calculated by solving for v:
v = (2gh)1/2 √2gh
- For problems with calculations use UDRSS: ◻Units ◻Data ◻Relationship ◻Substitution ◻Solution
ExampleA baby carriage is sitting at the top of a hill that is 10 m high. The carriage with the baby has a mass of 20 kg.
- Calculate the GPE: GPE=Gmh GPE = (9.8 m/s2)(10m)(20kg) = 1960 J
- Assume that GPE = KE
- Calculate the velocity: v = (2gh)1/2 = (2 · 9.8 m/s/s · 10m)1/2 = 14 m/s
- What is the carriage velocity if the hill is 5m?
- What is the carriage velocity if the carriage is 10 kg?