Forces and Motion

Question 1

Difference between speed and velocity

Answer 1

Speed - how fast you are going
Velocity - speed in a given direction

Question 2

Formula for speed

Answer 2

Speed = distance/time

Question 3

Formula for acceleration

Answer 3

Acceleration = change in velocity/time
v² = u² + 2as

Question 4

Describe distance-time graphs:
1. gradient?
2. flat sections?
3. steeper?
4. curves?

Answer 4

gradient = speed
flat sections = stopped
steeper = faster
curves = acceleration or deceleration

Question 5

Describe velocity time graphs:
1. gradient?
2. flat sections?
3. steeper?
4. Area under graph?
5. Uphill/downhill?

Answer 5

1.gradient = acceleration
2. flat sections = steady speed
3. steeper = greater acceleration or deceleration
4. Area under graph = distance
5. Uphill/downhill = acceleration/ deceleration

Question 6

Formula for weight

Answer 6

weight = mass × gravitational field strength

Question 7

Different types of force

Answer 7

1. gravity/ weight
2. reaction force
3. electrostatic force
4. thrust
5. drag/ friction/air resistance
6. lift
7. tension

Question 8

formula for force

Answer 8

force = mass × acceleration

Question 9

Three main ways of friction

Answer 9

Static friction (between solid surfaces, which are gripping)

Sliding friction (between solid surfaces, which are sliding past each other)

Resistance or drag (from fluids)

Question 10

Newton’s first law

Answer 10

An object has constant velocity unless acted on by a resultant force

Question 11

Newton’s second law

Answer 11

Force = mass × acceleration

Question 12

Newton’s third law

Answer 12

Every action force has an equal and opposite reaction force

Question 13

Newton’s third law

Answer 13

Every action force has an equal and opposite reaction force

Question 14

Difference between scalar and vector quantities

Answer 14

Scalar - has just a magnitude
Vector - has a magnitude and direction

Question 15

Examples of scalar and vectors

Answer 15

Scalar - distance, speed, time, energy

Vector - displacement, velocity, acceleration, force

Question 16

Effects of forces

Answer 16

Can change the speed, shape or direction

Question 17

Explain terminal velocity

Answer 17

When an object first starts to fall, it has much more force accelerating it than resistance, slowing it down

As its velocity increases, the resistance builds up

This resistance force reduces the acceleration until, eventually, the resistance force is equal to accelerating force

At this point, the object won’t be able to accelerate. It will have reached maximum velocity / terminal velocity

Question 18

What is the stopping distance and the formula

Answer 18

The distance covered in the time for the driver spotting the hazard and the car completely stopping

Stopping distance = thinking distance + braking distance

Question 19

Factors that affect thinking distance

Answer 19

1. How fast you are going
2. Your reaction time - tiredness alcohol, drugs, old age

Question 20

Factors affecting braking distance

Answer 20

1. How fast you are going
2. The mass of the vehicle
3. How good the brakes are
4. How good the grip is - road surface, weather conditions, tyres

Question 21

What is Hooke’s law

Answer 21

Force is proportional to the spring’s extension

F=kx

Question 22

Linear force-extension graph

Answer 22

Elastic deformation follows hookes law
The point the line stops being linear = limit of proportionality
After the limit of proportionality, it does not obey Hookes law

Question 23

Non-linear force-extension graph

Answer 23

deformation not following Hookes law
After this region, it will fracture

Question 24

What is elastic behaviour

Answer 24

A material that can return to its original shape once forces are removed