Forces- newtons laws

Force

A push or pull acting on an object due to an interaction with another object.

Resultant force

The sum of all the individual forces acting on an object (taking directions into account)

Calculating resultant force

Adding/minusing all the individual forces [depending on direction]

Newtons first law

“If the resultant force on a stationary object is zero, the object will remain at rest [stationary] or moving at a constant velocity [moving object]”

If an object changes direction but remains at a constant speed is there a resultant force?

Yes; since there is a change in direction there is a change in velocity

Zero resultant force

The object will remain staionary or at a constant speed

Inertia

The tendency of an object to continue in its state of rest or uniform motion

Equation for newtons second law

Resultant force= mass x acceleration

Newtons second law

An objects acceleration is directly proportional to the resultant force and inversely proportional to its mass

Inertial mass

• The measure of how difficult it is to change a given objects velocity

• Ratio of force over cceleration

• F=ma

Newtons third law

Whenever two objects interact the forces that they exert on each other are always equal and opposite

Weight

Force that acts on an object due to the mass and gravity

What factors does weight depend on

• objects mass

• Gravitational field strength

Unit used for weight

N [NEWTONS]

Earths gravitational field strength

10N/Kg

Approximate weight of a 1kg object on earth

10 newtons

Forces acting on a sky diver

Air resistance and weight

When does a falling object reach terminal velocity?

• when the upwards forces and the downwards forces are equal.

• No resultant force, so constant speed

Relationship between air resistance and velocity on a Falling object

As velocity increases so does the force of air resistance