1Change in Gravitational Potential Energy Equation
Change in G.P.E (J) = mass (kg) x gravitational field strength (N/kg) x change in height (m)
ΔG.P.E. = mgΔh
2What causes a change in an object’s G.P.E.?
A change in height
3When is energy transferred to an object’s gravitational store?
When an object's height increases
4When is energy transferred from an object’s gravitational store?
When an object's height decreases
5Kinetic Energy equation
Kinetic Energy (J) = ½ x mass (kg) x velocity² (m/s)
K.E. = ½mv²
6When does an object have kinetic energy?
When an object is moving (has some velocity)
7When is energy transferred to an object’s kinetic store?
When the object accelerates (when velocity increases)
8When is energy transferred from an object’s kinetic store?
When the object decelerates (when velocity decreases)
9Elastic energy store example
A spring / rubber band is stretched or compressed
10Electrostatic energy store example
Objects with charge (like protons or electrons) interacting
11Magnetic energy store example
Magnets interacting
12Chemical energy store examples
Energy in muscles
Fossil fuels
Batteries
13Nuclear energy store examples
Radioactive isotopes (used in nuclear reactors)
14Thermal energy stores in objects
All objects have energy in their thermal store
The hotter the object, the more energy in its thermal store
15Conservation of Energy definition
Energy cannot be created or destroyed, it can only be transferred
16Conservation of Energy in a closed system
Energy in a closed system remains constant
17Energy transfers when an object is projected upwards
Energy is transferred from the kinetic store to the gravitational store
(The object slows down but gains height)
18Energy transfers when an object goes up a slope
Energy is transferred from the kinetic store to the gravitational store
(The object slows down but gains height)
19Energy transfers when a moving object hits an obstacle
Energy is transferred from the kinetic store to the obstacle’s kinetic store or elastic store
(Object slows down but obstacle accelerates or collision causes deforming)
20Energy transfers when a person throws a ball
Energy is transferred from the person’s arm’s chemical store to the kinetic store of the ball
(Energy in the muscles is used up but the ball accelerates)
21Energy transfers in a rocket launching
Energy is transferred from the chemical store of the fuel to the kinetic energy of the rocket
(Fuel is burned but rocket accelerates)
22Energy transfer for a car slowing down
Energy is transferred from the car’s kinetic store to the thermal store of the brakes
(Car slows down but brakes heat up)
23Energy transfer for a kettle boiling
Energy is transferred from the thermal store of the heating element to the thermal store of the water
24Energy transfer for an object falling
Energy is transferred from the object’s gravitational store to kinetic store
(Object loses height but accelerates)
25Energy transfer for an object going down a slope
Energy is transferred from the object’s gravitational store to the kinetic store
(Object loses height but accelerates)
26Energy transfers in car accelerating
Energy is transferred from the chemical store of the fuel to the kinetic store of the car
(Fuel is burned and car accelerates)
27Energy transfers in person jumping on trampoline
Person has energy in kinetic store.
As they land on trampoline energy is transferred to the elastic store of the trampoline,
and then back to the kinetic store of the person as they bounce back up.
As the person goes up, the energy in their kinetic store is transferred to their gravitational store.
They start falling again and energy is transferred back to the kinetic store, restarting the process.
28When a system is in equilibrium... (energy transfers)
Nothing changes so no energy is transferred
29When a system changes... (energy transfers)
Energy is transferred between energy stores within the system
There is no change in total energy in the system