Zusammenfassung der Ressource
PHYSICS
- Energy
- 'A measure of what
an object can do'
- Jules (J)
- 10 types
- Law of Conservation of Energy:
Cannot be made, created or
destroyed - only transferred on
type to another
- Work done
- work done= force x distance
- J
- Power
- power = energy/time
- W
- Efficency
- efficiency = useful energy/total energy
- %
- Renewable/Non-renewable
- Renewable
- Used at same speed/slower than
can be created
- Non-renewable
- Used faster than can be created
- 4 main types:
- Gas
- Oil
- Uranium (nuclear)
- Coal
- Motion & Forces
- Speed
- speed = distance/time
- m/s
- Velocity
- Speed + DIRECTION
- Acceleration - rate of change of velocity
- acceleration = change in velocity/time
- m/s²
- Deceleration is negative
- How fast it's going.
- 10 forces
- Gravitational:
between 2/more
objects with mass
- nc
- Weight: btwn objects with
mass, specifically the
smaller one
- nc
- Friction: btwn surfaces
trying to slide/sliding
past each other
- c
- Air resis.: air particles
colliding with an object
as it moves though air.
- c
- Water resis.: Water
particles colliding with
an object as it moves
through water.
- c
- Upthrust; Pressure
in fluid pushing
objects upward
- c
- Electric: btwn 2/more
objects with net charge
(+/-)
- nc
- Magnetic: btwn
magnets/a magnetic field
and a magnetic material
- nc
- Tension: caused on
the other end of a
pulled objected
- c
- Reaction: the push from
any object/surface
when a force is applied
- c
- Contact
(c)
/Non-contact
(nc)
- Freebody diagrams
- Length of the arrow shows
size of force and direction
shows which way the force
is acting on the object
- Weight/mass
- Weight - the force
on an object due to
mass and gravity.
- Measured in N
using a
Newtonmeter
- Mass - the amount of
matter an object has.
- Measured in kg/g
with a balance
- weight = mass x
gravitational
field strength
- N
- Gravity on earth is 9.8N/kg
- The moon's gravity is
1.6N/kg
- Newton's Laws of Motion
- 3. There are no isolated forces, for
every force acting on an object there is
one of equal size but opposite
direction which acts back on the
object. All forces have an equal but
opposite reaction force.
- 1. An object will remain at rest or
move at a constant speed in a
straight line unless acted upon by
unbalanced forces. This means that
an object with balanced forces will
stay still or continue to move at the
constant speed.
- 2. If unbalanced forces act upon an
object then the object will change
speed or direction. This is called
acceleration. The amount an object
accelerates is determined by the mass
of the object and the net force acting
on it.
- acceleration = force/mass
- m/s²
- Hooke's Law
- Hooke's Law is summarised by
a formula. This is used to work
out how much a spring will
stretch when a given force is
applied.
- force = spring constant x
change in length
- N
- Electricity
- Electricity is the
movement of charged
particles, generally
electrons.
- Conductors/Insulators
- A conductor allows
electricity to flow
through because it
has many free
electrons.
- Examples: metals,
especially gold, silver
and copper
- Insulators have very
high resistance - they
do not have many free
electrons, making it
hard for electricity to
flow through.
- Examples: non-metals,
glass most plastics
- Drawing circuits
- Cell - converts
chemical
energy to
electrical.
- Battery -
multiple cells
- Bulb - converts
electrical energy into
light and wasted heat
energy.
- Switch - used to
control a
circuit.
- Resistor - decreases
the current in part of a
circuit.
- Ammeter -
measures the
current in a
circuit. Connected
in series.
- Voltmeter - measures
the voltage in a
circuit. Connected in
parallel.
- Buzzer - converts
electrical energy to
sound.
- Motor - converts
electrical energy to
kinetic.
- LED - converts
electrical
energy to light
energy.
- Diode - only allows
current to flow in
one direction.
- Variable resistor -
used to vary the
amount of current
flowing through a
circuit.
- Fuse - if the current is
too high, the fuse
melts and breaks the
circuit to protect the
item being powered.
- LDR - changes
resistance in
light intensity.
- Thermistor -
changes
resistance in
light intensity.
- Current
- Current is the rate
of flow of charge.
- The charge in a
circuit is generally
electrons.
- The unit is amps (A).
- Measured with
an ammeter.
- 1000 mA in 1A
- Voltage
- Voltage is the energy
per unit charge.
- The unit is
volts (V)
- Measured
with a
voltmeter.
- Parallel/Series Circuits
- Series
- In series, everything
is connected in one
loop.
- The voltage is split between
components, meaning
bulbs are dimmer.
- The current stays the
same everywhere in a
circuit.
- Pros/Cons
- Pros: cheaper
& easier to
make, uses
less wires
than parallel.
- Cons: unable to
turn components
on/off
independently, if
part of the circuit is
broken/damaged
none of it works &
bulbs are dimmer.
- Parallel
- In parallel,
there are
lots of
loops
connected.
- Current is split at
junctions, so is
different all around
the circuit.
- Voltage is not
split, same
everywhere.
- Pros/Cons
- Pros: components can
turn on/off
independently, brighter
bulbs & if part breaks
the rest works.
- Cons: more
expensive
and harder to
make & uses
more wires.
- Power
- Power has two formulae
- power = energy/time
- W
- power = current x voltage
- W
- Unit is watts (W)
- Power is the
rate at which
energy is
transferred.
- Resistance
- Resistance is
how hard it is
for a current to
flow in a circuit.
- Measured in ohms (Ω)
with an ohmmeter
- Caused by free
electrons colliding
with ions.
- Resistance is
increased the longer
a wire is or the more
components there
are in a circuit.