physics 2 defs

distance

Total length travelled. (m)

displacement

 position of the object relative to the start in a straight line (m)

scalar

Quantities with magnitude (size or number) only

vector

Quantities with magnitude and direction. 

Can be represented by arrows.

magnitude

The size of a quantity

direction

Which way something moves relative to a starting position of system of coordinates

speed

the distance travelled in a given time.

constant/uniform

non-changing

acceleration

The change in velocity per unit time

deceleration

Negative change in velocity (slowing down)

independant variable

The variable deliberately changed in the experiment

dependent variable

The variable which is measured in response to changes to the independent variable

controlled variable

The variables that need to be kept constant in an experiment to ensure valid results

velocity

Velocity is the displacement per unit time

random error

When the measurement differs from the actual value in an unpredictable manner

systematic error

When the measurement differs from the actual value by the same amount.

precision

Refers to the fineness of a scale

accuracy

Refer to how close the measured value is to the accepted value

force

A force is an interaction between two bodies that causes a change in motion (speed and/or direction), or a change in shape of the objects.

resistance

A force which opposes the motion of an object

newton

unit of force (N)

unbalanced forces

When forces act on an object and they do not cancel each other. The total force on the object is the unbalanced force

balanced forces

When multiple forces at on an object, but they cancel each other out. (sum of forces are equal size but opposite in direction.)

equilibrium

When the total force acting on an object is zero

mass

amount of matter in an object (kg)

weight

gravitational force acting on a body towards the centre of Earth

resultant

The one force that has the same effect as the individual forces acting on an object. (e.g total force)

action

The applied force (object 1 on object 2)

reaction

The force in response to the applied force. It is equal in size but opposite in direction of the applied force. (This force is produced by object 2 and is applied to object 1)

normal force

The reaction force from an object pressing into a surface. The direction of this force is always perpendicular to the surface.