Energy Changes In A System Flashcards
What is the equation for kinetic energy?
0.5 × mass × v2
What is the equation for elastic potential energy?
0.5 × spring constant × x*2
What is the equation for gravitational potential ?
Mass × Gravitational Field Strength × Height
Define specific heat capacity of a substance
The amount of energy needed to raise the temperature of 1 kilogram of a substance by 1 degree Celsius
State the units for Specific Heat Capacity
J/°C/kilogram
What is the definition ‘Power’
The rate at which energy is transferred.
State 2 equations for power
Power = energy transferred/time
Power = work done /time
What is the unit of power
Watts (W)
Two motors lift the same mass through the same height. Motor A does this in half the time of motor B.
Which dissipates the most power?
Motor A
The energy transferred is the same but the time taken is less
Describe the energy changes involved when a ball is thrown upwards and then returns to it’s starting position. Ignore air resistance.
Upwards: GPE
Downward: GPE is converted to KE
Describe the energy transfer for a bungee jumper
When falling the GPE is converted to KE of jumper
As the cord tightens KE is converted and stored as Elastic Potential Energy
(EPE)
Explain why a bungee jumper slows down once the cord begins to stretch
KE energy decreases since it is converted to elastic potential energy
Give examples of chemical energy stores
Food
Fuel ( wood,coal, petrol)
Batteries
State 4 different stores of energy
Kinetic Energy
Gravitational Potential Energy
Elastic Potential Energy
Chemical Energy
