Scalars & Vectors, Contact forces vs Non-contact forces

What is a scalar quantity?

A quantity that only has magnitude.

What is a vector quantity?

A quantity that has both a magnitude and direction.

Name some scalar quantities:

Distance, speed, mass, energy, temperature, power, volume, density

Name some vector quantities:

Displacement, velocity, weight, acceleration, momentum, force

How can vectors be represented?

By an arrow, the length of the arrow represents the magnitude of the vector and the direction of the arrow indicates the direction of the vector.

What is a force?

A push or pull force that acts on an object due to the interaction with another object.

What are the 2 kinds of forces?

Contact & Non-contact forces.

What is weight?

The force acting on an object due to gravitational attraction.

What is a contact force?

A force that acts between 2 objects that are physically touching.

Give 3 examples of contact forces:

1. Friction - force that opposes motion

2. Air resistance(drag) - friction of the air on a moving object

3. Tension - force that pulls 2 objects connected by a length

4. Reaction force - a force that pushes touching objects apart

What is a non-contact force?

A force that acts at a distance, without any contact between bodies - due to the action of a field.

Examples of non-contact forces:

• Gravity

• Electrostatic force

• Magnetic force

What is a force pair?

When there is an interaction between two objects, a force is exerted on each object.

Describe the force pairs present with respect to a rock being pushed by a person.

• The applied force that the person exerts on the rock is opposed by a reaction force from the rock.

• The weight of the rock on the ground is opposed by a normal force

• The weight of the person is also opposed by a normal force

• The force applied by the person driving their feet into the ground is opposed by friction