9: Forces and their effects

**Balanced Forces**

A resultant force of 0

Contact Force

A force that acts on an object through physical contact

Electrical Field

A region where a change will experiance a non-contact electrostatic force

Equilibrium

An object in equilibrium has 0 resultant force and 0 resultant moment

Force Field

A region where an object will experiance a non-contact force

Force Vectors

An arrow that represents a force where the length represents its magnitude and the arrowhead indicated the direction

Free body diagram

A visual representation of the forces that act on an object

Friction

A resistive contact force that acts to oppose the relative motion between 2 surfaces

Gears

A simple mechanism that can transmit the rotational effect of a force

Gravitational Field

A region where a mass will experiance a non-contact gravitational force

Lever

A simple mechanism that can transmit the rotational effect of a force

Lubrication

The application of a lubricant to reduce friction

Magnetic Field

A region where a magnetic material will experiance a non-contact magnetic force

Moment

The turning effect of a force

Moment =

force x distance from pivot to the line of action of the force

newton metre

unit of a moment

non-contact force

a force that acts on an object at a distance

Principle of moments

for an object in equilibrium, the sum of the clockwise moments must be equal to the sum of the anti clockwise moments

resolution of forces

all forces can be resolved into 2 perpendicular components that have the same effect as a single force

resultant force

the single force that can replace all individual forces acting on an object and have the same effect

resultant moment

the single moment that has the same effect as the sum of all the other moments acting on an object

scalar quantities

quantities that only have a magnitude, not a direction

vector quantities

quantities that have both magnitude and direction