forces and motion

scalar

a quantity that has a magnitude only

vector

a quantity that has a magnitude and a direction

distance

how far an object moves, or the length of the shortest line between two points

displacement

distance in a given direction

speed

the rate at which a moving object covers distance, measured in m/s

average speed

the speed of a moving object over an entire journey or section of a journey

instantaneous speed

the speed of a moving object at a particular moment in time. calculated from a distance time graph using a tangent line

velocity

speed in a given direction

accelaration

the change in velocity per second

deceleration

negative accelaration

distance time graph

the gradient of this graph equals the speed of the object\na straight line shows constant speed\na horizontal line shows a stationary object\na curved upwards or downwards line shows acceleration or deceleration

velocity time graph

the gradient of the graph equals the acceleration of the object\nan upwards sloping straight line shows constant acceleration\na downwards sloping straight line shows constant deceleration \na horizontal line shows constant speed (zero deceleration)

tangent

a straight line used to calculate the gradient of a curved line at a specific point.

gradient

choose any two points on the line and label them (x1, y1) and (x2, y2) .\nuse the formula (y2 -y1) divided by (x2 - x1) \nthe result is the gradient

extension

the increase in length of an object when pulled in two opposite directions by forces. calculated by subtracting the unstretched length from the stretched length

compression

when an object decreases in length, height or thickness due to forces acting on it

elastic

any material that returns to its original shape when the forces acting on it are removed

directly proportional

values directly proportional to each other will produce a straight line passing through the origin when plotted on a graph

hooke's law

up to a maximum force, the size of a stretching object is directly proportional to the extension of the object

limit of proportionality

the maximum force an elastic object can be stretched with and still return to its original shape when the force is removed

force extension graph

used to see whether an object is elastic

elastic potential energy

when an elastic object is stretched it becomes a store of elastic potential energy

force

a push or a pull. all forces are vector quantities

terminal velocity

the maximum speed an object reaches when falling through a fluid