Paper 2 - forces

Question 1

What is a force?

Answer 1

A push or pull
Acts on another object
Measure in newtons (magnitude)
Has direction

Question 2

What is the difference between a contact and non-contact force?

Answer 2

Objects are physically touching in contact
Non-contact force don’t require objects touching

Question 3

What are examples of non-contact forces?

Answer 3

Gravitational
Magnetic
Electrostatic

Question 4

What are examples of contact forces?

Answer 4

Friction
Air resistance
Tension

Question 5

What is a scalar quantity? And e.g.

Answer 5

Magnitude (size)
E.g. Distance, time, temperature, mass, speed

Question 6

What is a vector quantity? And e.g.

Answer 6

Magnitude and direction
E.g. momentum, velocity, force, acceleration, displacement

Question 7

How do you represent vectors?

Answer 7

Using arrows
Length = magnitude
Way its pointing = direction

Question 8

How do we find the resultant force from free body diagrams?

Answer 8

As the forces are acting in different directions, some will cancel each other out leaving the resultant force

Question 9

What is extension?

Answer 9

Increase in length of a spring when its stretched

Question 10

What are moments?

Answer 10

Rotational or turning effect of a force

Question 11

What happens with gases in a container?

Answer 11

Collide into the walls exerting a force along the normal

Question 12

The braking distance of a car increases as the speed of the car increases.
Give two other factors that increase the braking distance of a car.

Answer 12

Icy roads
Poor condition of brakes or tyres
Increased mass of car

Question 13

Explain why the driver’s reaction time affects the thinking distance of a car.

Answer 13

d = s x t
so longer reaction time = longer distance

Question 14

What is meant by ‘centre of mass’?

Answer 14

The point from which weight may be considered to act

Question 15

What is the equation for weight?

Answer 15

W = mass x 9.8

Question 16

How do you find the spring constant?

Answer 16

Spring constant = force/length

Question 17

What does distance have to be when calculating moment?

Answer 17

Perpendicular from the line of action of the force to the pivot

Question 18

What happens to the moment when an object falls?

Answer 18

There is a resultant moment acting on the object

Question 19

What happens to density when altitude increases?

Answer 19

It decreases

Question 20

What is the rule with upthrust?

Answer 20

Pressure of a liquid increases with depth
As depth increases there is a greater weight of liquid acting downwards