Energy, Waves & Electricity Simplified!
speed= - distance/time
acceleration= - change in velocity / time taken
V²= - U²+2as
acceleration is... - how quickly the velocity is changing
weight= - mass x gravitational field strength
gravitational field strength on earth - 10N/kg
a force is... - a push or pull
friction increases... - as the speed increases
Newton's first law of motion - balanced forces mean no change in velocity
Newton's Second Law of Motion - if there is an unbalanced force, then the object will accelerate
in that direction
Newton's Third Law - For every action there is an equal and opposite reaction
force= - mass x acceleration
a vector... - has magnitude and direction
a scalar... - has magnitude only
Hooke's Law - Extension is directly proportional to force until the spring reaches it's elastic
limit
Hooke's law stops working... - when the force is great enough
stopping distance= - thinking distance + braking distance
factors effecting thinking distance - how fast you are going, your reaction time
factors effecting breaking distance - how fast you are going, mass of the vehicle, how good the
breaks are, how good the grip is
momentum= - mass x velocity
, momentum units - kg m/s
momentum conservation principle - momentum is conserved when no external forces
act
momentum before= - momentum after
Force causes a change in momentum: force= - change in momentum/ time
Force causes a change in momentum: F= - (mv-mu)/t
crumple zones - Crumple on impact, increasing the time taken for the car to stop
seat belts - stretch slightly increasing time taken for the wearer to stop
air bags - slow you down more gradually
a moment... - is the turning effect of a force
moment= - force x perpendicular distance from pivot moment units -
Nm principle of moments - The sum of the clockwise moments is equal to the sum of
the anticlockwise moments.
a.c - alternating current
d.c - direct current
(resistance current voltage) voltage= - current x resistance
resistance units - Ohms
wire graph - line straight through the origin
filament lamp graph - curve
Different resistors graph - all straight lines through the origin; different gradients
diode graph - current only flows in one direction
LED - Light Emitting Diode
LDR - Light dependent resistor
Thermistor - A resistor that changes its resistance with a change of temperature
Ammeters are connected in - series