physics - 1: motion, forces and energy

straight-line section of a distance-time graph

Speed from the gradient

Acceleration

change in velocity per unit time

Mass

a measure of the quantity of matter in an object at rest relative to the observer

Gravitational field strength

force per unit mass

Spring constant

force per unit extension

Moment formula

Moment = force x perpendicular distance

Impulse formula

force x change in time = change in mv

conservation of momentum

P1 before + p2 before = p1 after + p2 after

Energy stores

Kinetic
gravitational potential
Chemical
Elastic
Nuclear
Electrostatic
Magnetic
Internal (thermal)

Energy transfers

By forces - mechanical work done
Electrical currents - electrical work done
Heating
Electromagnetic
Sound

Work done formula

W=Fd= change in E

Useful energy may be obtained/electrical power generated from

chemical energy stored in fossil fuels
Chemical energy stored in biofuels
Water, tides, hydroelectric dams
Geothermal resources
Nuclear fuels
Light from the sun to generate electricity (solar cells)
Infrared (solar panels)

Generators

Water strikes the blades of a turbine to make it turn
Turbine is connected to generator which produces electricity

energy sources that radiation from the sun is not the main source of energy for

geothermal, nuclear, tidal

Power

work done per unit time/ energy transferred per unit time

power formulae

P=W/t
P=change in E/t

scalar quantity

only magnitude

vector quantity

magnitude and direction

scalar quantities

distance
speed
time
mass
energy
temperature

vector quantities

force
weight
velocity
acceleration
momentum
electric field strength
gravitational field strength

velocity formula

V = s/t

Velocity

speed in a given direction

Average speed formula

Average speed = total distance/total time

Acceleration of free fall

constant (9.8 m/s^2)

Acceleration formula

final velocity-initial velocity/time

gradient of a speed-time graph

Acceleration

terminal velocity

the maximum velocity that an object can attain when it is falling through a fluid, such as air or water

Weight

a gravitational force on an object that has mass

weight formula

W=mg

Density

mass per unit of volume

Density formula

ρ=m/v

Spring constant formula

k=F/x

Limit of proportionality

The point at which the graph goes from being a straight line to a curved line

force formula

F=ma

equilibrium

When there is no resultant force and no resultant movement

Center of gravity

the average location of all the weight of an object

Momentum formula

p=mv

Resultant force

the change in momentum per unit time

kinetic energy formula

Ek= ½mv^2

Gravitational potential energy formula

Eg=mgh

Turbine

Fuel provides heat energy to boiler
Water changes to steam
Turns blades of turbine
Turbine is connected to generator which produces electricity

PV (photovoltaic) solar cells

solar cells convert light energy into electrical
OR use a solar panel to heat water

efficiency energy formula

% = (useful energy output/total energy input) x100

efficiency power formula

% = (useful power output/total power input) x100

Pressure

force per unit area

pressure formula

p=F/A

Liquid pressure formula

p=ρgh

Area under a speed-time graph

distance travelled for motion with constant speed or constant acceleration

Deceleration

negative acceleration

effects of forces

direction
acceleration
change in size
change in shape

resultant force formula

F=change in p/change in time

Energy generation methods

Turbine
Generators
PV (photovoltaic) solar cells

how is energy released by the sun

nuclear fusion