Forces Motion And Electricity Flashcards
Unit of speed and velocity
M/s
Speed is…
Velocity is…
Speed is how fast you are going
Velocity is the same but the direction is also specified
Acceleration =
Change in velocity/tine
What is acceleration
How quickly the velocity is changing
Distance time graphs
Gradient = speed Steeper is faster Flat is where stopped Downhill is going back to starting point Curves are accel or deccel
Velocity time graphs
Gradient = acceleration
Flat is steady speed
Steeper is greater accel or deccel
Curve is changing acceleration
Weight =
mass x gravitational field strength
Terminal velocity
A final speed you hit when falling, it is related to its weight and drag
First law of motion
Balanced forces mean no change in velocity
Second law of motion
If there is an unbalanced force than the object will accelerate in that direction
Another word for this is the resultant force
Third law of motion
Reaction forces
If you push on something it pushes back and the smallest mass is accelerated further
Resultant force =
F
Mass x acceleration
Stopping distance =
Whole time to stop
Braking distance + thinking distance
Thinking distance
And factors
Distance car travels for driver to react and apply brakes
Speed
Reaction time/state (tired or drunk)
Braking distance
And factors
The distance car travels during brakes on to stop
Speed
Mass of vehicle and people inside
State of brakes
Grip - road weather. Tyres.
Momentum =
(P)
Kg m/s
Mass x velocity
Momentum before =
Momentum after
Force =
Change in momentum/time taken for change to happen
Crumples zones
Crumple on impact to increase the time taken for a car to stop
Seat belts
Stretch slightly to increase the time taken for a wearer to stop
Reduce force on chest
Air bags
Also slow you down more gradually
A moment is a
Turning effect of a force
Moment (nm) =
Force (n) x perpendicular distance between line of action and pivot
Centre of gravity
Directly below the point of suspension
Force causing orbits
Gravity
Gravity decreases as
You get further away
Some orbits are
Elliptical (elongated)
For a circular orbit the distance travelled is the
Circumference
Orbital speed =
(2 x pi x orbital radius)/time
Speed =
Distance/time
plastic is an…
insulator
the live wire
red wire
alternates between high voltage and low voltage of about 230V
the neutral wire
blue
always at zero V
elect flows through live and out neutral
earth wire
green/yellow (colorblind)
connected to power supply and is a back up wire
there in case fault with main wires
connected to the ground
fuse/circuit breakers
melt when current is too high to stop shocks or fires
circuit breaker more convenient than fuses because
switch- faster
switch-can be switched back on, fuse has to replace
power =
current x voltage
Pee on the IVy
energy transferred =
j
current x voltage x time
Ee on the IVy Tea
Resistance =
ohms
Voltage/current
diodide
graph goes steady then upwards curve
high resistance one way
current the other way
metal filament lamp
curve then constant up then curve
wire
current through a wire is proportional to voltage
LDR light dependent resistor
line box with arrows line
downwards curve, resistance decreasing with light intensity
resistor used in light sensing units
thermistors
line- box with line through on a diagonal -line
a temp-dependent resistor
temp sensors
hot conditions, resistance drops
charge =
charge measure in coulombs C
current x time
series circuit
all components one after the other along the wire
disconnect and circuits breaks
fairy lights
current same everywhere
parallel circuits
disconnect one and will hardly affect others
each component has its own loop
how most things are
household lights
one volt is
one joule per coulomb
static electricity cause
caused by friction
two insulators rub each other
one + electrostatic charge loss electrons
one - electrostatic charge gain electrons
which way depends on material
+ +
+ -
- -
repel
attract
repel
charged rod test
suspend a rod with known charge
bring another rod towards it
if attraction, test rod has opposite charge of suspend rod
if repel, test rod is same charge as suspend rod
generators that make your hair stick up
Van de Graaff generators
static helpful
inkjet
photocopier
static problem
lightning
fuel (gas stations)
1 amp
1 coulomb per sec
voltage =
energy/charge
electron charge
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