Energy Stores
This energy store increases as an object increases in temperature
Thermal
What is the unit of measurement of energy?
Joules
What is the unit of Power?
Watt
What is the equation for work done?
Work = Force x Distance
Name 3 Renewable Sources of Energy
Wind, Solar, Tidal, Wave, Hydroelectric, Geothermal, Biomass
If an object is falling, this energy store is decreasing
Gravitational Potential
What is weight?
A downward force due to gravity
What is the equation for power?
P = E/t
or P = IV
What variables affect the kinetic energy of an object?
Mass and Velocity
What is a disadvantage of Solar Power
No sun no power
Which energy store is stored in objects that are stretched or compressed?
Elastic
What is the work done on an object when 500N are used to push a box 15m?
500 x 15
=7500J
What energy store is considered "wasted" or not useful energy
Thermal
How do you calculate kinetic energy?
1/2 x Mass x Velocity2
What is a unit for energy used when calculating the cost of energy
kWh, Kilowatt hours
What is the law of conservation of energy?
Energy cannot be created or destroyed. Only transferred
A 4kg box is put on a 2m high bookshelf on Earth. How much gravitational potential energy has it gained?
4 x 9.8 x 2
=78.4J
What do you need to know to work out the efficiency of an appliance
Useful energy and Total energy
How strong is gravity on Earth?
9.8
Why is coal used for energy instead of renewables?
Cheaper, More reliable, relatively efficient compared to renewables
The name given to the store of energy within atoms
Nuclear
What is kinetic energy on a 20kg object that is falling at 15m/s?
0.5 x 20 x 152
=2250J
How much energy is used in a 50W TV that is on for 60 seconds
50 x 60 = 3000J
If an object is thrown upwards. When is kinetic energy the lowest?
At the highest point
A microwave with a power of 1000W is used for 30 minutes. How many kWh has it used
1000 x 0.5 = 500kWh