# Kinetic Energy

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• Created by: cchastney
• Created on: 04-10-15 19:35
• Kinetic Energy
• Forces and Energy
• Work done and energy transfer measure in Joules (J). The work that's done uses the equation W = F x d. W stands for work done. F stands for force applied (Newtons) and d stands for distance moved in force's direction (metres).
• Power shows how fast work is done, which equals how fast energy is transferred. To calculate power this is the equation P = E / t. P stands for power (watts). E stands for work done (joules) and t stands for time taken (seconds).
• Gravity potential energy is stored energy we have on Earth's surface. It depends on mass an height above ground. The calculation is Ep = m x g x h. Ep stands for change in GPE (J), m is mass (kg), g is gravitational field strength (N/kg) and h is change in height (m)
• Momentum
• Momentum changes if a force is applied to an object which is moving/can move.
• Momentum is contained in objects which can move. Objects are unable to have their direction changed if they have lots of momentum, unlike objects with little momentum which can be moved much easier. Momentum can change if an object speeds up/slows down or changes direction.
• Momentum is calculated using the equation p = m x v. P stands for momentum (kg m/s). M stands for mass (kg). V stands for velocity (m/s).
• Momentum remains the same in collisions and explosions, unless an external force acts upon it. In collisions/ explosions, momentum is conserved because it stays the same.
• Every object which can move has kinetic energy, it depends on mass and speed. To calculate it, the equation is Ek = 0.5 x m x v2. Ek is kinetic energy (J), m is mass (kg) and v is speed (m/s).
• Kinetic energy is transferred in a pendulum due to the ball transferring GPE into KE and back. At the highest swing point there's no kinetic energy, but there's maximum GPE when it swings down GPE becomes KE and there's acceleration. At the bottom of the swing, there's maximum KE, but no GPE. Whilst it swings KE transfers into GPE. Energy is transferred as surrounding heat when the ball becomes lower in every swing.