Week 1 Flashcards
What is the formula for kinetic energy? (symbols and what they are measured in).
Ek = 1/2M x V2
Joules Kg m/s
What is the formula for gravitational potential energy? (symbols and what they are measured in).
Ep = M x G x H
Joules Kg N/kg M
What is the formula for elastic potential energy? (symbols and what they are measured in).
Ee = 1/2 K x e2
Joules spring constant(stiffness)N/m extension(how
far it has extended)
What is the rule about energy in a closed system?
Energy cannot be created or destroyed, only transferred.
What is the equation for power?
Power = Energy/Time
Watts Joules Seconds
What is convection?
Convection can happen in liquids and gases, when air is heated it rises and its density decreases. Because liquids and gases can flow, the warmer areas rise above the colder areas. If there is a constant heat source, a convection current has been formed.
What is specific heat capacity?
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degree Celsius.
What is the equation for specific heat capacity?
Energy = Mass x specific heat capacity x change in temperature
E m c Theta
Energy = Joules
mass = Kg
Specific heat capacity = J/Kg°C
Change in temperature = °C
How do you reduce unwanted energy transfers?
Lubrication
Home insulation
Streamlining
How do you reduce energy transfer in homes?
- Loft insulation
- Cavity wall insulation
- Double glazing
- Draught excluders
- Thicker walls
- Walls with low thermal conductivity
What is the formula for efficiency?
Efficiency = Useful power output/total power input
Examples of non-renewable energy resources?
- Coal
- Oil
- Gas
- Nuclear
Examples of renewable energy resources?
- Solar
- Wind
- Water waves
- Hydro-electricity
- Bio-fuel
- Tides
- Geothermal
What are energy resources used for?
- Heating
- Transport
- Generating electricity
What is current?
The rate of flow of charge (electrons)
What is the unit for current?
Amps
What is the unit for resistance?
Ohms
What is the equation for charge?
Q = I x T
Q = Charge flow - Coulombs I = Current - Amps T = Time - seconds
What is the equation for potential difference?
V = I x R
V = Voltage - Volts I = Current - Amps R = Resistance - Ohms
What is the practical for investigating resistance?
- Attach a crocodile clip at 0 cm.
- 2nd crocodile clip at 10 cm.
- Record the current ant the voltage.
- Move 2nd crocodile clip another to 20 cm
- Record current and voltage
- Repeat for different lengths
- Then use the V = I x R to figure out the resistance
What are the rules in series circuits?
- Current is the same at any point
- Voltage is shared between components (components with bigger resistance have bigger share of pd)
- Total resistance is the sum of the individual resistors
