Forces and Motion

Question 1

Units for acceleration due to gravity

Answer 1

m/s² or N/kg

Question 2

What is a vector quantity

Answer 2

A quantity with a magnitude and direction eg. velocity

Question 3

What is a scalar quantity

Answer 3

A quantity that has a magnitude but no direction eg. mass

Question 4

What is acceleration measured in?

Answer 4

m/s²

Question 5

What is Newton’s first law?

Answer 5

An object will stay at rest or continue to move at a constant speed in the same direction unless acted upon by a resultant force

Question 6

How do you find the resultant force of two objects?

Answer 6

Find the difference between both forces

Question 7

What factors affect the thinking distance of a person in a car?

Answer 7

Alchohol
Poor visibility
Old age
Tiredness
Drugs

Question 8

What factors can affect the stopping distance of a car?

Answer 8

• Its mass
• Its speed
• The driver’s reaction time
• The condition of the brakes
• The road conditions
• Amount of friction between the tyres and road

Question 9

What is speed?

Answer 9

How fast an object is moving

Question 10

What is velocity?

Answer 10

Speed in a certain direction

Question 11

What is distance?

Answer 11

How far something has or will travel

Question 12

What is displacement?

Answer 12

Distance in one direction as the fastest route

Question 13

Give some examples of vector quantities

Answer 13

• All forces (eg. Weight)
• Velocity
• Displacement values

Question 14

Give some examples of scalar quantities

Answer 14

• Energy
• Speed
• Mass

Question 15

How are vector quantities shown on diagrams?

Answer 15

With arrows

Question 16

What does a flat line mean on a distance time graph?

Answer 16

The object is stationary

Question 17

What does a curve represent on a distance time graph?

Answer 17

Acceleration or deceleration

Question 18

What does a straight line mean on a distance time graph?

Answer 18

Object is stationary

Question 19

What does a flat line mean on a velocity time graph?

Answer 19

The object is travelling at a constant speed

Question 20

What does a diagonal line mean on a velocity time graph?

Answer 20

Acceleration or deceleration

Question 21

How do you find the distance travelled in a velocity time graph?

Answer 21

You work out the area under the graph

Question 22

How do you work out the acceleration on a velocity time graph?

Answer 22

Use the equation

Question 23

Describe an object’s motion if the resultant force is 0

Answer 23

Either:

• It will be travelling at a constant speed
• It will be stationary

Question 24

What different resistive forces could be acting on a car when in motion?

Answer 24

• Air resistance
• Friction
• Contact force

Question 25

What is terminal velocity?

Answer 25

The **maximum velocity of an object**, reached when the forces moving the object are balanced by its frictional forces

Question 26

What is thrust?

Answer 26

A force used to move something forwards or up

Question 27

What are balanced forces?

Answer 27

When the resultant force is 0

Question 28

If two forces are balanced, what is the resultant force?

Answer 28

0

Question 29

Is the moon travelling at a constant velocity?

Answer 29

No, because is not moving in a constant direction

Question 30

What is constant velocity?

Answer 30

When something is travelling at a constant speed in a constant direction

Question 31

What is the name of the force bringing something forward?

Answer 31

Driving force

Question 32

What is Newton’s second law?

Answer 32

*F = ma*

Question 33

What is inertial mass?

Answer 33

The ratio of force over acceleration *m = F/a*

Question 34

What is Newton’s third law?

Answer 34

For every action there is an equal and opposite reaction

Question 35

What are the 4 criteria for Newton’s third law pairs?

Answer 35

The forces must be: - Equal in magnitude - Acting in the opposite direction - The same type of force - Acting on different objects

Question 36

Give an example of a Newton third law pair

Answer 36

The gravitational force of the Earth on the Moon **and** The gravitational force of the Moon on the Earth

Question 37

Stopping distance = ???

Answer 37

Thinking distance + braking distance

Question 38

What factors affect the braking distance of a car?

Answer 38

- Its mass - Its speed - The condition of the brakes - The condition of the road - The amount of friction between the tyre and the road surface

Question 39

What factors affect a drivers reaction time (thinking distance)?

Answer 39

- Age - Alcohol or drugs - Poor visibility - Tiredness - Distractions

Question 40

What is the equation for momentum?

Answer 40

Momentum = mass x velocity

Question 41

What are the units for momentum?

Answer 41

Kg m/s

Question 42

What is the conservation of momentum?

Answer 42

The principal that in a collision the total momentum before the event is equal to the total momentum after the event.

Question 43

How does a crumple zone help in a car crash.

Answer 43

A crumple zone will change the shape of a car during a crash. If the change in momentum happens over a longer time, there is less force, shown by the equation F = mv-mu/t

Question 44

What is the typical speed of sound?

Answer 44

330 m/s

Question 45

What is the typical cycling speed of a person?

Answer 45

6 m/s

Question 46

What is the typical running speed for a person?

Answer 46

3 m/s

Question 47

What is free fall?

Answer 47

The acceleration due to gravity

Question 48

Name 3 car safely features designed to reduce the time of a collision

Answer 48

- Seat belts - Air bags - Crumple zones

Question 49

How do wet roads affect the stopping distance of a car?

Answer 49

Increases braking distance as wet roads reduce friction between the road and the car tyres

Question 50

What is centripetal force?

Answer 50

The resultant force of an object travelling in a circle, acting towards the centre of the circle

Question 51

Describe the relationship between the rate of change of momentum and the force

Answer 51

They are directly proportional

Question 52

How do you calculate the braking distance of a car?

Answer 52

- Find the work done (E) to stop it - This is the same the kinetic energy of the car (1/2mv²)

Question 53

How do you calculate gear ratio?

Answer 53

Amount of teeth on driven gear ——————————————— Amount of teeth on driver gear

Question 54

What is a moment?

Answer 54

A turning force

Question 55

Which of these will be able to cut through tougher stuff and why: - Long handled scissors - Short handled scissors

Answer 55

The longer handled scissors, because the distance normal to the direction of the force is directly proportional to the moment

Question 56

Describe the relationship between clockwise and anticlockwise moments when an object is at equilibrium

Answer 56

The sum of clockwise moments = The sum of anti-clockwise

Question 57

Name two methods for determining the speed of an object

Answer 57

- Dropping a ball from a height of 1m and measuring the time taken - Using light gates

Question 58

What is the typical speed of a car?

Answer 58

10-30 m/s

Question 59

What is the typical speed of a plane?

Answer 59

200-250 m/s

Question 60

What is the acceleration in free fall?

Answer 60

10 m/s²

Question 61

Describe an object’s motion if the resultant force is not 0

Answer 61

It **accelerating/decelerating** and/or **changing direction**

Question 62

What is weight?

Answer 62

The force due to gravity on an object

Question 63

Describe the relationship between the weight of an object and the gravitational field strength

Answer 63

They are **directly proportional**

Question 64

How does a higher speed affect the stopping distance of a car?

Answer 64

The faster the car is travelling, the larger the breaking distance