Mechanics Vocab

Level 2 NCEA Physics

Centripetal force

The centre-seeking unbalanced force that causes acceleration.

Removal of centripetal force

Object will travel in tangent to circle.

Distance travelled in speed time graph

Area under line.

Scalar

Quantity that only has size (magniturde). E.g distance.

Vector

Quantity that has size and direction. E.g displacement.

Gradient of speed time graph

Gives acceleration

Gradient of distance time graph

Gives speed of object graphed

Vertical acceleration when object moving upwards

acceleration = -9.8 ms^-2

Vertical acceleration when object moving downwards

acceleration = +9.8 ms^-2

Resultant

The ‘answer’ when a number of vectors are added or subtracted

Components

The vertical and horizontal

Reference frame

A commonly understood way of describing the direction of vectors

Displacement

How far from a particular point something is, includes a direction.

Distance

How far an object has travelled

Velocity

The rate of change of displacement, or more simply speed with direction

Speed

How fast something is moving

Acceleration

The rate of change of velocity or more simply a change in motion.

Freefall

When an object ‘falls’ towards the ground continuously accelerating at 9.8 ms^-2.

Projectile

An object moving through the air only under the influence of gravity; only force/acceleration is downwards. Path is called a trajectory and is parabolic in shape

Projectile motion

Combination of vertical motion with constant acceleration due to gravity, and horizontal motion with constant velocity (no acceleration).

Torque

Force that causes objects to rotate.

Pivot

Point that object rotates around.

No rotational movement

Torques acting on object are in equilibrium. (sum of clockwise torque = anticlockwise torque).