# P3 Physics The Energy of Games and Theme Rides

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• Created by: A.P
• Created on: 21-01-13 19:38
• The Energy of Games and Theme Rides
• Gravitational Potential Energy
• An object held about the ground has gravitational potential energy.
• This is shows by the formula GPE = mgh, where m = mass, h = vertical height moved and m = gravitational field strength (10N/kg).
• GPE is measured in Joules (J).
• Energy Transfers
• A bouncing ball converts GPE into kinetic energy and back to GPE. It does not return to its original height because energy is transferred.
• When skydivers reach terminal speed, their kinetic energy (1.2mv2) has a maximum value and remains constant. The gravitational potential energy lost as they fall is used to do work against friction (air resistance).
• When terminal speed is reached is can be shown as: Change in GPE = Work Done against Friction.
• How a Roller Coaster Works
• A roller coaster uses a motor to haul a train up in the air. The riders at the top of a roller coaster ride have a lot of gravitational potential energy.
• When the train is released it converts GPE to kinetic energy as it falls. Loss of GPE = Gain in KE.
• Ignoring Friction, as the train falls mgh = 1/2mv2.
• h = (mv2)/(2mg) = (v2)/(2g). So this is independent of the mass of the falling object.
• Each peak is lower than the one before because some energy is transferred to heat and sound due to friction and air resistance.
• This is shown by the formula: GPE at top = KE at bottom + Energy Transferred (To Heat and Sound) Due to Friction.