Physics yr9 Flashcards
How can energy be stored
In a variety of different ways
Name 4 different ways energy can be transferred
Heating, waves, electrical current or when an object is moved
What happens when an object falls and gains speed
Its store of gravitational potential energy decreases and its kinetic energy store increases.
What happens when a object hits the ground and it bounces back
Kinetic energy store increases
Can energy be created or destroyed
No
Does conservation of energy apply to all energy changes
Yes
What is a closed system
A system in which no energy transfers take place out of or into the energy stores.
Can energy be transferred between energy stores in a closed system
Yes
What happens when an object moves up and down
Gravitational potential energy:
Increases when it moves up
Decreases when it moves down
What happens when an object is lifted up
Gravitational potential energy store increases.
Is the gravitational potential field strength at the moon’s surface less than on earth
Yes
True or false
The energy in the kinetic energy store, depends on its mass and speed
True
What energy is stored in an elastic object when work is done on it.
Elastic potential energy
What is the name given to energy when it is in the place we want it and in the form we need it.
Useful energy
What is the name given to the energy that is not useful and is transferred by an undesirable pathway
Wasted energy
What happens when wasted energy is eventually transferred to the surroundings
It becomes warmer
What happens as energy dissipates (spreads out)
It gets less and less useful
True or false
An energy transfers can be more than 100% efficient
False
What substances supply most of the energy we use in our house
Gas and/ or oil
What is a wind turbine
An electricity generator on the top of a tall tower
How do waves generate electricity
By turning a floating generator
How does hydroelectricity generate energy
Generators are turned by water running downhill
How does a tidal power station generate energy
Traps each high tide and uses it to turn generators.
What are solar cells
Flat solid cells that use the suns energy to generate electricity directly
How do solar heating panels heat water
Using the suns energy
Where does geothermal energy come from
Energy transferred by radioactive substances deep inside the earth
How do they produce steam to drive turbines
By pumping water into hot rocks
Do nuclear fuels produce harmful waste
Yes
How many cells does a battery consist of
Two or more
What does the size of an electrical current =
Rate of flow of charge
What is the equation for the electrical current of a circuit
I=Q/t
How do you find potential difference across a circuit
V=E/Q
How do you find the resistance
R=V/I
What is ohms law
The current through a resistor at a constant temperature is directly proportional across its ends
What are the characteristics for the components in a series
- the current is the same in each component
- the total potential difference is shared between the components
- adding their resistance gives the total resistance
How do we find the total resistance
R total = R1+R2
Does adding more resistors in series increases the total resistance
Yes
What are the characteristics for the components in a parallel
- the total current is the sum of the currents through the separate components
- the potential difference across each component is the same
True or false
The bigger the resistance of a component, the smaller the current that will pass through it
True
What is the equation for the current through a resistor
I=V/R
What happens if we add more resistors in a parallel circuit
The total resistance decreases
