Studied by 52 people
Different types of energy stores
Gravitational Potential Energy
Kinetic Energy
Thermal Energy
Chemical Energy
Elastic Potential Energy
What is the conservation of energy?
The conservation of energy is that energy cannot be created or destroyed, only transferred from one form to another.
What energy transfers happen when bungee jumping?
Gravitational potential energy is converted to kinetic energy as the jumper falls. Kinetic energy is then transferred to elastic potential energy as the bungee cord stretches. Finally, the elastic potential energy is converted back to kinetic energy as the jumper rebounds upward.
What is the equation for work done?
Force applied x Distance
What is work done transferred into to overcome friction?
Thermal energy
What is the equation for gravitational potential energy store of the change in an object?
Weight x Change of height
Equation for Gravitational Potential Energy
Mass x Gravitational Field Strength x Change of Height
Equation for Kinetic energy
½ x Mass x velocity²
Equation for elastic potential energy
½ x spring constant x extension²
What is hooke’s law?
The extension of a spring is proportional to the force applied within the elastic limit
What is useful energy and wasted energy?
Useful energy - energy transferred to where it is wanted the way it is wanted
Wasted energy - energy that is not fully transferred
What is dissipation?
When the energy that is not fully transferred (wasted energy) spreads out and can be stored in less useful ways
Why is there always wasted energy in machinery?
Friction is always the cause to wasted energy in machines e.g when using a drill, the friction causes heat which is wasted
Equation for efficiency
Useful output energy / Total input energy
Friction, the resistance of a wire, air resistance and sound are all causes of wasted energy in machinery. Describe a way to reduce the wasted energy for each one
Friction - using lubricants, reducing friction
The resistance if a wire - use wires with less electrical resistance
Air resistance - streamlining the shapes of moving objects to reduce air resistance
Sound - tighten looser parts to cut out sound caused by vibration
What is the useful and wasted energy in a hairdryer?
Useful energy: Kinetic energy (air from fan) and energy heating air
Wasted energy: Sound energy and the hairdryer heating up
Equation for power
Energy transferred / Time
Equation for efficiency (including useful and total power input)
Useful power output / total power input x 100
Equation for wasted power
wasted power = total power input - useful power output
Equation for force
mass x acceleration
Note
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