# Physics KS3 Forces (January 2023) (in order) Flashcards

1
Q
1. What is a force?
A

A force is a push or pull that acts on an object

2
Q
1. Forces are measured in ……. (units)
A

Newtons or N / (N must be uppercase)

3
Q
1. To measure a force the instrument you use is a …….
A

newtonmeter or forcemeter or spring balance

4
Q
1. Sometimes the two bodies must be touching for the force to be present these are called ……. forces.
A

Contact

5
Q
1. Sometimes one body can have an effect on another without having to be in contact, these forces are known as ……. forces.
A

Non-contact

6
Q
1. Description: Forward push of an object moving on a solid surface – Name the force and state whether contact or non-contact
A

Thrust/Forward force – Contact

7
Q
1. Description: Attraction (pull towards) or repulsion (push away) of magnets and magnetic materials – Name the force and state whether contact or non-contact
A

Magnetism/Magnetic – Non-contact

8
Q
1. Description: Attraction between two objects with mass (Gravity) – Name the force and state whether contact or non-contact
A

Weight – Non-contact

9
Q
1. Description: Upward push of water on an object – Name the force and state whether contact or non-contact
A

Upthrust – Contact

10
Q
1. Description: Upward push of a solid surface on an object – Name the force and state whether contact or non-contact
A

Normal contact – Contact

11
Q
1. Description: Force which slows objects moving along a solid surface – Name the force and state whether contact or non-contact
A

Friction – Contact

12
Q
1. Description: Force which slows objects moving through water – Name the force and state whether contact or non-contact
A

Water resistance/drag – Contact

13
Q
1. Description: Force which slows objects moving through air – Name the force and state whether contact or non-contact
A

Air resistance/drag – Contact

14
Q
1. Description: The force pushing up on an object as it moves through the air, caused by differences in air pressure. – Name the force and state whether contact or non-contact
A

Lift – Contact

15
Q
1. Description: Forces caused when objects eg springs, string are stretched/compressed – Name the force and state whether contact or non-contact
A

Tension/Compression – Contact

16
Q
1. A number of forces acting on an object may be replaced by a single force that has the same effect as all the original forces acting together. This single force is called the ……………… force.
A

resultant

17
Q
1. What is the resultant force when the forces on an object are balanced?
A

Zero or 0 N

18
Q
1. State the effect of unbalanced forces on a moving object if the resultant force direction is in the direction that the object is moving. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

3) It will speed up

19
Q
1. State the effect of balanced forces (zero resultant) on a moving object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

2) It will keep moving at a constant speed

20
Q
1. State the effect of balanced forces (zero resultant) on a stationary (not moving) object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

1) It will stay stationary

21
Q
1. State the effect of unbalanced forces on a stationary (not moving) object. Which of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

3) It will speed up

22
Q
1. State the effect (if any) of unbalanced forces on a moving object if the resultant force is in the opposite direction to the direction of the moving object. Which one of the following is true? 1) It will stay stationary 2) It will keep moving at a constant speed 3) It will speed up 4) It will slow down
A

4) It will slow down

23
Q
1. How can friction between solid objects be reduced?
A

Lubrication eg oil on bike chains or wax on snowboards

24
Q
1. How can drag forces such as water resistance or air resistance be reduced?
A

Streamlining/use streamlined shapes

25
Q
1. If you’re talking about how much of a substance there is, are you talking about Mass or Weight?
A

Mass

26
Q
1. If you’re talking about a force, are you talking about Mass or Weight?
A

Weight

27
Q
1. If you’re talking about something measured in Newtons, are you talking about Mass or Weight?
A

Weight

28
Q
1. If you’re talking about something that changes from planet to planet, are you talking about Mass or Weight?
A

Weight

29
Q
1. If you’re talking about the kg, are you talking about Mass or Weight?
A

Mass

30
Q
1. If you’re talking about the Newton/N, are you talking about Mass or Weight?
A

Weight

31
Q
1. If you’re talking about something that doesn’t change from planet to planet, are you talking about Mass or Weight?
A

Mass

32
Q
1. Remember that Weight = Mass x Gravitational Field Strength. If Mass = 1kg and Gravitational Field Strength = 10 N/kg, what is Weight?
A

Weight= 1 x 10 = 10 N

33
Q
1. Remember that Weight = Mass x Gravitational Field Strength. If Mass = 0.1kg (100g) and Gravitational Field Strength = 10 N/kg, what is Weight?
A

Weight= 0.1 x 10 = 1 N

34
Q
1. Remember that Weight = Mass x Gravitational Field Strength. If Mass = 0.2kg (200g) and Gravitational Field Strength = 10 N/kg, what is Weight?
A

Weight= 0.2 x 10 = 2 N

35
Q
1. Remember that Weight = Mass x Gravitational Field Strength. If Mass = 2kg and Gravitational Field Strength = 2 N/kg, what is Weight?
A

Weight= 2 x 2 = 4 N

36
Q
1. The Moon has a gravitational field strength of 1.6 N/kg whereas Earth has a gravitational field strength of 9.8 N/kg? What does this tell us about the relative mass of the Earth and the Moon?
A

The Earth has more mass than the Moon

37
Q
1. Why do surfaces that feel smooth still have friction?
A

Even smooth surfaces have microscopic hills and valleys (which resist movement)

38
Q
1. What force causes surfaces to wear away over time?
A

friction

39
Q
1. In addition to wearing away surfaces what other effect does friction cause when rubbing two objects together?
A

A rise in temperature

40
Q
1. Describe 2 uses of friction between solids
A

Without friction our feet would not be able to grip the road and we would be unable to walk / Friction is important in helping objects to slow down safely using brakes / [Also to strike a match]

41
Q
1. Describe a benefit of air resistance
A

Air resistance is the force that parachutes make use of to slow down someone who is falling from an aeroplane

42
Q
1. Why doesn’t a rocket in space need to use its engine to keep moving?
A

There is no friction or air resistance in space to slow it down. [Gravity is not zero in space]

43
Q
1. State the equation for speed
A

Speed = Distance/Time

44
Q
1. When distance is measured in metres and time is measured in seconds, what is speed measured in?
A

m/s

45
Q
1. Calculate the speed of an object moving a distance 10 m in 2 s.
A

Speed = Distance/ Time= 10 /2 = 5 m/s

46
Q
1. What word is used to describe an object that is speeding up?
A

Acceleration or accelerating

47
Q
1. For a spring what do we call the stretched length minus the unstretched length?
A

Extension

48
Q
1. What is the name of the law that springs obey? The law says that a spring’s extension doubles when the force doubles or extension is directly proportional to the stretching force.
A

Hooke’s Law

49
Q
1. Describe a risk assessment for the spring experiment
A

Hazard: Spring could break or come loose / Risk: damage eye / Precaution: Wear safety goggles