year 9 science - energy Flashcards
state the law of conservation of energy
energy cannot be created or destroyed, but rather transformed from one form to another, with the total amount of energy in a closed system remaining constant
energy efficiency formula
efficiency=(useful energy output/total energy input)x100
ohms law formula and what it means
V = I x R
V is voltage (V)
I is current (A)
R is resistance (Ω)
power formula
P = W/T
P is power (Watts)
W is work (J)
T is time (s)
OR
P = V x I
P is power (watts)
V is voltage (V)
I is current (A)
elements of a complete circuit
- conductive path (wires)
- power source (battery)
- load (resistors, light bulb etc.)
series vs parallel circuits
series - one path for current
parallel - multiple paths for current
non-renewable energy sources
- coal
- oil
- natural gas
- nuclear
renewable energy sources
- solar
- wind
- hydro
- geothermal (heat within the earth eg. hot springs, volcanoes)
- biomass (plants)
ways to improve energy efficiency
- use energy efficient appliances (star rating)
- reduce energy waste (turn off unused devices)
- improve insulation in buildings
- use renewable energy sources
kinetic energy formula
*the faster something moves the more kinetic energy it has
KE = 1/2 mv²
KE is kinetic energy (Joules)
m is mass (kg)
v is velocity (minutes/second)
so therefore, kinetic energy = half of (mass x velocity squared)
gravitational potential formula
*higher objects have more potential energy
GPE = mgh
GPE is gravitational potential energy
m is mass (kg)
g is gravity (9.8m/s²)
h is height (m)
kinetic vs potential
KE = energy of movement
PE = stored energy due to position
TYPES OF ENERGY (there are 11 (three potential energies)
- Kinetic energy
- Potential energy
- gravitational potential energy
- elastic potential energy
- chemical potential energy - Thermal energy
- Electrical energy
- Light energy
- Sound energy
- Nuclear energy
- Mechanical energy
mechanical energy formula
ME = KE + PE
