4.5.1 Forces and their interactions

What is a scalar quantity?

Magnitude only

What is a vector quantity?

Magnitude and direction

What are examples of a scalar quantity?

Speed, distance, time, mass, energy

What are examples of a vector quantity?

Velocity, displacement, acceleration, force, momentum

What is a force?

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

What are the two forces between all objects?

Contact and non-contact

What are examples of non contact forces?

Electrostatic, gravitational, magnetic

What are examples of contact forces?

Normal contact force, friction, air resistance, tension

What is weight?

The force acting on an object due to gravity

What is the equation for weight?

weight = mass x gravitational field strength

What is weight measured by?

A force meter

Explain weight if the same person is on two different planets?

Their mass will be the same but the gravitational field strength at the two planets will be different so their weight will be different on both

What is a resultant force?

A single force representing the sum of all the forces acting on an object

Using a skydiver as an example, describe the forces acting on the diver?

Initially, the skydiver has no air resistance and the only force acting on him is weight. As he falls, he accelerates, increasing his speed. As air resistance increases, the resultant force from weight decreases so acceleration decreases so he’s not speeding up as quickly. Eventually they are equal so there’s no resultant force and the diver is travelling at terminal velocity

How do you solve resolving forces?

Using Pythagoras’ rule