Physics - forces in balance

What is scalar?

A quantity that only has magnitude (size) but no direction.

What is vector?

A physical quantity that has magnitude and direction

What is displacement?

A distance moved in a particular direction by an object (e.g 10m west)

What is distance?

The total distance moved by an object

Is displacement scalar or vector?

vector

Is distance scalar or vector?

scalar

Contact force

These forces occur when two objects physically touch each other

Normal force

The perpendicular pushing force exerted by a surface on an object resting on it

Frictional force

The resistance force that opposes the motion (or attempted motion) of two surfaces sliding or touching each other. Includes static and kinetic (sliding) friction

Tension force

The pulling force transmitted through a string, robe, cable, or wire when it is pulled tight by forces acting from opposite ends

Applied force

A direct push or pull exerted on an object by a person or another object

Spring force

A restoring force exerted by a spring when it is stretched or compressed trying to return to its natural resting length

Air resistance (drag)

A fictional force that opposes the motion of an object as it travels through air or another fluid.

Non-contact force

Forces that act over a distance without any physical contact between the objects, operating through a surrounding force field

Non contact force examples

Magnetic, gravitational, electrostatic

Contact force examples

friction, air resistance, tension and normal contact force

Gravitational force

An attractive force that acts between any two objects that have a mass

Electrostatic/ electric force

The attractive or repulsive force between charged particles

Magnetic force

The attraction or repulsion that arises between magnetic poles or moving electric charges

Rules to drawing a vector diagram

• The vector arrow length indicates the magnitude of the vector

• Vectors of the same magnitude should have the same length of vector arrow

• Vectors of a smaller or larger magnitude should have a shorter or longer vector arrow

• Write the scale you have used to draw your diagram next to the diagram

Free Body Diagram

Shows the relative magnitude and direction of all forces acting up in an object in a given situation - type of vector diagram

Newton’s first law

if the forces acting on an object are balanced, the resultant force is zero i.e if the object is at rest it remains stationary and if the object is moving it remains at a constant velocity

Unbalanced forces newtons law

When the resultant force of an object is not zero, the forces acting on the object are not balanced. The movement of the object depends on the size and direction of the resultant force