Topic 9: Forces and their effects

Question 1

Explain the difference between vector and scalar quantities

using examples

Answer 1

A scalar is a force with a magnitude without a direction, e.g: volume, density and speed.
A vector is a force has both a magnitude and a direction, e.g: velocity and gravitational field strength.

Question 2

What is a force?

Answer 2

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

Question 3

What are two categories that all forces split into?

Answer 3

Non contacts forces

Contact forces

Question 4

3 examples of contact forces

Answer 4

Tension
Air resistance
Friction

Question 5

3 examples of non contact forces

Answer 5

Gravitational forces
Electrostatic forces
Magnetic forces

Question 6

Examples of scalar quantities

Answer 6

Temperature
Time 
Speed
Mass
Distance
Temperature

Question 7

What is another name for the turning effect of a force?

Answer 7

A moment!

Question 8

Equation for moment of a force

Answer 8

Moment of force = force x perpendicular distance

Question 9

If an object is in equilibrium, what can we say about the moments acting on the object?

Answer 9

Clockwise moments are equal to the anti clockwise moments

Question 10

How do levers make use of moments?

Answer 10

They increase the perpendicular distance to the pivot so less force needed to produce same moment.

Question 11

How are levers used to decrease the force required to lift something?

Answer 11

Levers use the pivot point and concept of moments to reduce force. So the further away you are from pivot, less force needed to lift object.

Question 12

How does lubricating gears/ leavers improve efficiency?

Answer 12

Less resistance, so less energy dissipated to surroundings as heat, overcoming frictional forces.