P1 Flashcards
What are the 5 main types of energy stores?
Chemical
Thermal
Gravitational Potential
Elastic
Kinetic
What is the name of the energy store associated with a compressed spring?
Elastic Potential
What is the name of the energy store associated with a book on a high shelf?
Gravitational Potential
What is meant by a closed system?
An object or a group of objects in which no energy transfers take place out of or into the energy stores of the system
In terms of energy stores, what happens when you turn on a torch?
Energy is transferred from the chemical energy store of the battery (by the electric current in the wire between the battery and the bulb) tot eh thermal energy store of the surrounding (by light waves and by heating)
What does the conservation of energy mean?
Energy cannot be created or destroyed
What is the S.I unit of energy?
Joule, J
What is the formula for Work done?
Work done = Force x Distance
W =F x s
What is the formula for change in gravitational potential energy?
Change in gravitational potential
= mass x gravitational field strength
x change in height
What happens to the gravitational al potential energy store of an object when the object moves downwards?
It decreases
What is the unit of gravitational field strength?
Nwetons per kilogram
N/kg
What is the formula for kinetic energy?
Kinetic energy = 0.5 x mass x velocity squared
What is the formula for elastic potential energy?
Elastic potential energy
= 0.5 x spring constant x extension squared
What makes an object elastic?
An object is described as being elastic if it regains its original shape after being stretched or squashed
What is wasted energy?
Wasted energy is energy that is not usefully transferred?
What happens to the wasted energy from a light bulb?
It is dissipated to the surroundings which will warm up
Why should we talk about energy being wasted and not energy being lost?
Energy cannot be created or destroyed, so it cannot be lost; but is wasted when it is not transferred correctly
What is the formula for efficiency?
Efficiency = useful energy transferred ÷ total energy supplied to the device x 100
The shape of a lorry is modified to reduce air resistance. What happens to the efficiency of the lorry?
It increases
How is energy wasted by a toaster?
By heating the surroundings and the body of the toaster
How is energy usefully transferred by a toaster?
By heating the bread
What sit the formula for Power?
Power = energy ÷ time
What unit is Power measured in?
Watts , W
How many Watts are equivalent to 2.2kW?
2200
What is the power of an appliance
The rate at which it transfers energy
What is the principle of conservation of energy?
Input energy = useful output energy + energy wasted
