Forces

Question 1

What is a scalar force?

Answer 1

A scalar has a size (magnitude) and no direction. E.g speed

Question 2

What is a vector?

Answer 2

Vectors have both size and direction. E.g velocity

Question 3

Give a couple of examples of contact forces.

Answer 3

Air resistance and friction

Question 4

Give a couple of examples of non-contact forces?

Answer 4

Gravitational forces and magnetic forces.

Question 5

What is the link between weight and mass?

Answer 5

Weight and mass are proportional, whenever weight goes up (for example double) mass will also go up (by double in this case)

Question 6

What is defined as the centre of mass?

Answer 6

The centre of mass is defined as where an object’s weight acts.

Question 7

What is a resultant force?

Answer 7

A resultant force is when a single force can replace all the other forces acting on something (due its larger size)

Question 8

What happens when an object is moved against a force?

Answer 8

work is done on it.

Question 9

What is work done measured in?

Answer 9

Jules (J)

Question 10

What is force measured in?

Answer 10

Newtons (N)

Question 11

What is distance measured in

Answer 11

Meters (m)

Question 12

What is extension measured in?

Answer 12

M (meters)

Question 13

What is the relationship between force and extension? When does this relationship cease?

Answer 13

Force and extension are proportional unless you go past the limit of proportionality. There is a linear relationship up until this point.

Question 14

What is elastic deformation?

Answer 14

When you take the force off the spring and it returns to its original length.

Question 15

What is inelastic deformation?

Answer 15

When you apply too much force and when you take it off the spring and it does not return to its original length.

Question 16

When a force is applied to a spring, what will happen to it and what energy will it have?

Answer 16

When a force is applied to the spring it will extend and change shape, it will have elastic potential energy stored.

Question 17

What is elastic potential energy?

Answer 17

Elastic potential energy is energy stored in a system when work is done to change its shape.

Question 18

What is the difference between distance and displacement?

Answer 18

Distance is how far you have gone. Displacement is how you are from one point and can be a positive or a negative.

Question 19

What is the speed of sound in air and how can this very with different materials?

Answer 19

The speed of sound in air is around 330m/s. The more dense a material is, the faster it will take for sound it travel in it, e.g sound moves much faster in iron or brick or even water than air.

Question 20

What is speed measured in?

Answer 20

Meters per second (m/s)

Question 21

What does it mean when there is a straight line on a distance time graph?

Answer 21

A straight line means that the speed is constant (even when stationary).

Question 22

What is acceleration measured in?

Answer 22

Meters per second squared (m/s^2)

Question 23

What does it mean when there is a straight line going downwards on a velocity-time graph?

Answer 23

The straight line means that the object is going in a constant speed, but because it is going downwards it means that it will be negative.

Question 24

What is terminal velocity? What happens once you reach it?

Answer 24

When the forces are balanced so the speed becomes constant. When you reach terminal velocity you cannot go any faster in the position.

Question 25

What is Newton’s first law of motion?

Answer 25

A body will remain at rest or will continue at a constant velocity if no resultant force acts, e.g when a resultant force acts forwards on a car it will accelerate.

Question 26

What is inertia?

Answer 26

Without an unbalanced force while moving at a constant velocity you would continue to move at a constant velocity, this is called inertia.

Question 27

What is Newton’s second law of motion?

Answer 27

The acceleration of a body is proportional to the resultant force causing it to accelerate. It is inversely proportional to the mass of the object.

Question 28

What is inertia mass a measure of?

Answer 28

Inertia mass is a measure of how difficult it is to change the velocity of an object

Question 29

What is Newton’s third law of motion?

Answer 29

When body A exerts a force on body B, body B exerts an equal and opposite force on body A, e.g when you row a canoe the force you apply to the top of the paddle forwards will also be applied to the the water backwards causing you to move.

Question 30

What is stopping distance?

Answer 30

Thinking distance (reaction time) + Braking distance (the time it takes for you to do the action).

Question 31

What are some things that can affect someone’s time to think (their thinking distance)?

Answer 31

Drugs, alcohol, tiredness, poor visibility and their speed.

Question 32

What is momentum made up of?

Answer 32

Any object with both mass and velocity has momentum.

Question 33

What is a normal contact force?

Answer 33

When two objects are physically touching, e.g lamp on a table, a lamp is exerting a downward force on the table and the table exerts an upward force on the lamp

Question 34

What is the centre of mass?

Answer 34

the weight of an object which acts at one point

Question 35

Whats the difference between mass and weight?

Answer 35

Your mass stays the same everywhere but your weight depends on your GPE/ gravitational field strength

Question 36

What’s a typical walking speed?

Answer 36

1.5m/s

Question 37

What’s a typical running speed?

Answer 37

3m/s

Question 38

What’s a typical cycling speed?

Answer 38

6m/s