IGCSE
Physics Notes: Useful Things Worth Knowing
The pressure of a column of
gas or liquid is independent of the area. This is because
and
the area is not mentioned.
In the absence of air
resistance, a feather falls with the same acceleration as a
cannon ball.
Hence if both are released
from the same height at the same time, they will reach the ground at
the same time.
If you double the speed of a
car, you don't double the braking distance. You multiply by 4. If the
speed of the car is tripled the stopping distance is multiplied by 9.
This is because
Silver/shiny things heat up
more slowly than black/dull things because they are worse at
absorbing radiation. Silver/shiny things cool down more slowly than
black/dull things because they are worse at emitting radiation.
The resistance of a
thermistor or semiconductor decreases if the temperature increases.
If the thermistor is in a circuit with a voltage, then the current in
the circuit may increase and the voltage across the thermistor may
decrease.
Materials with higher
specific heat capacities take long to heat up and heat up less for
the same amount of energy.
Materials with higher latent
heats of vapourization or fusion need more energy to evaporate or
melt.
Less of the material is
evaporated or melted for the same energy input.
Friction is always present.
If energy is lost during a process it is usually because work has to
be done to overcome friction or air resistance.
When anything is melting or
evaporating the temperature is constant.
If
then
and
BE
SURE YOU LEARN HOW TO REARRANGE THESE SIMPLE EQUATIONS.
The distance travelled is
equal to the area under a velocity time graph. The acceleration is
equal to the gradient of a velocity time graph.
Heavier things take longer
to slow down than light things, if the braking or resistance force is
the same. This means they will travel further before they stop.
A moving magnet will make
charge move and produce a current and a moving charge – a current –
will induce a magnetic field.