newtons third law states for every action, there is an equal but opposite reaction. this means that all forces come in Pairs. within these pairs, two forces have equal size but they act on different bodies In opposite direction
stability, the lower the centre of gravity is the more stable the object. the centre of gravity must remain over the base to remain stable and not topple
a moment is the turning effect of a force, moments act about a point (Pivot) in a clockwise or anticlockwise direction
principles of movement, if an object is balanced the total clockwise moment about a pivot equals the Total anticlockwise moment about that pivot, f1 x d1 = f2 x d2
moment equation, moment = force x distance perpendicular to turning force
centre of gravity is a point from which the weight of a body or system may be considered to act. gravity is concentrated at this point, all force of gravity is exerted
forces, is push, pull, stretch, lift, throw applied to an object. it can change the speed, shape or direction of an object. there are contact and non contact forces. it is a vector quantity as it has a direction
force equation, force = mass x acceleration. force is measured in N. mass is measured in kg. acceleration is measured in ms
the velocity of an object is the speed of an object in a given direction, it is a vector quantity
average speed equation, average speed = distance travelled divided by time taken. distance is measured in m. time take is measured in s. speed is measured in ms
speed is a measure of how far an object moves in a given time, it is a scalar quantity so no direction is involved, it is measured in ms
magnetic force is force cause by a magnetic field, non contact
weight equation, weight = mass x gravitational field strength
elastic force is force related in stretching and compressing an object, contact
tension is force applied to hang an object, contact
air resistance is force due to contact between an object and air, contact
weight equation, weight = mass x 10, the unit is newton's per kilogram
weight is force due to gravity, non contact
newtons 2nd law states the acceleration of an object is proportional to the resultant force of an object and inversely proportional to the mass of the object
factors affecting vehicle stopping distance include, driver tiredness, phone distractions, poor visibility, level of tire inflation, car conditions such as poor brakes, speed
buoyancy is force caused by the pressure of water, contact
scalar quantity has only magnitude and no direction, examples include speed, distance, mass, energy, temperature and time
displacement is a vector quantity that gives the net distance from start to finish with a direction, measured in m
friction is the force due to contact between two surfaces, contact, it always acts against the direction of motion
forces that act along a line, subtract the magnitude of the smaller force away from the magnitude of the larger force. the direction of the resultant force is the same as the direction of the larger force
resultant force is the sum of all forces acting on an object, if the resultant force is not 0 the forces on the object are said to be unbalanced, the object will therefore change velocity this can be a change in speed, direction or both
vector quantity has a magnitude and direction, examples include force, velocity, displacement, weight, acceleration and momentum
distance is how far an object moves it is a scalar quantity so does not involve direction. measured in m
electrostatic force, force exerted by a charged particle or a charged object, non contact
terminal velocity is as it gains speed objects weight stays the same but the air resistance on it increases. there is a resultant force acting downwards, eventually the objects weight is balanced by the drag/air resistance. there is no resultant force and the object reaches a steady speed called terminal velocity. drag upwards, weight downwards
hookes law the extension of a spring is directly proportional to the force applied until it reaches its elastic limit or proportional is not exceeded, stiffer the spring higher the spring constant
extension of spring equation, extension of spring = stretch length x final length
force, spring constant equation - force = spring constant x extension
acceleration equation, acceleration equals change in velocity divided by change in time. acceleration is measured in ms2 velocity is measured in ms time is measured in s
if an object speed up, velocity increases and the acceleration is positive. if an object slows down, velocity decreases and the acceleration is negative, deceleration
velocity time graph, the line is the gradient, flat sections are steady speed, stepper means accelerating or decelerating, curve means changing acceleration
distance time graphs, flat sections means stopped, steeper means faster, curves mean acceleration, levelling off curve means deceleration, speed = change in vertical divided by change in horizontal
final speed 2 equation, final speed 2 = initial speed 2 + (2 x acceleration x distance moved)