P5- Forces

What is a force?

a force is a push or pull that can change an objects motion or shape

Whats a scalar quantity?

quantities with magnitude but no direction

Whats a vector quantity?

quantities with magnitude and direction

what are the 2 main types of forces?

Contact and Non-contact forces

What are examples of contact forces?

Air resistance ,normal contact force and tension

What are examples of Non- contact forces?

Magnetic force, Electrostatic force and Gravitational force

What is Friction?

A contact force that acts between two surfaces touching.
It opposes motion and tries to slow things down.

What is Gravitational Force?

A non-contact force that pulls masses towards each other.
On Earth, it pulls objects downwards — this is their weight.

What is Electrostatic force?

A non-contact force between charged objects.

• Opposite charges attract

• Same charges repel

What is Magnetic Force?

A non-contact force between magnets or magnetic materials.

• Opposite poles attract

• Same poles repel

What is Mass?

mass is the amount of matter in an object

What is Weight?

Weight is the force due to gravity that is acting on an object with Mass

How is Weight different from Mass?

Mass is the amount of matter in an object and is measured in kilograms.
Weight is the force acting on an object due to gravity and is measured in newtons

Explain why the weight of an object changes when it is taken from Earth to the Moon. (2 marks)

because the weight of an object is is influenced by the Gravitational Field Strength where the object is located

State 2 factors that affect the gravitational field strength at a point. (2 marks)

• Planet the object is on

• distance from the centre of planet

What is the Gravitational Field Strength on earth?

9.8N/Kg

What is the equation for Calculating Weight?

Weight = mass × gravitational field strength

What is the units for Weight?

Newtons(N)

What is the units for Mass?

Kilograms(Kg)

What is the unit for Gravitational field strength?

Newtons per kilogram(N/Kg)

Explain what the equation Weight = mass × gravitational field strength tells us about the relationship between weight and mass. (2 marks)

Weight is directly proportional to the Mass of an object

How do we convert grams to kilograms?

divide by 1000

How do we convert Kilograms to grams?

multiply by 1000

What is a resultant force?

The overall force acting on an object when all individual forces are combined

what does resultant force determine?

whether an object stays at rest, moves or accelerates

what happens if the forces are balanced?

0N No change in motion

what happens if the forces are unbalanced?

the object acclerates

How to calculate resultant force?

• forces in the same direction- add them

• forces in opposite directions- subtract the smaller from the larger

What is the equation for calculating force?

Force = mass × acceleration

What is the units for force?

Newtons(N)

What is the units for mass?

Kilograms(Kg)

What is the units for acceleration?

metres per second squared(m/s²)