P2.2 -Forces Flashcards Preview

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Flashcards in P2.2 -Forces Deck (70)
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1
Q

what happens in an interaction pair (N3)?

A
  • forces act in opposite directions

- each force is the same magnitude

2
Q

what is newton’s third law?

A

“when two bodies interact, they exert a force upon each other that is equal in size, but opposite in direction”

3
Q

state three non-contact forces?

A
  • gravity
  • electrostatics
  • magnetism
4
Q

how does gravity interact with objects?

A

attracts them

5
Q

how do electric charges interact with objects?

A
  • attract and repel
6
Q

what is a field of a force?

A

the region where an electric charge, a magnetic material or a mass experiences a force

7
Q

how are forces represented?

A

with a force arrow

8
Q

where does a force arrow start on an object for a non-contact force?

A

the centre

9
Q

where do you draw contact force arrows from?

A

the point of contact

10
Q

use what you know about the structure of the atom to suggest why a non-contact force is produced within an atom

A
  • there are electrons on the outsides of atoms.
  • As you push them together they repel.
  • This is an electrostatic force, which is a non-contact force.
11
Q

what is terminal velocity?

A

the velocity at which a body falls through a medium, when the drag acting on the body is equal to its weight

12
Q

what planes do we consider when explaining the motion of an object at an angle?

A
  • the plane perpendicular to the slope

- the plane parallel to the slope

13
Q

what is air resistance?

A

when an object moves through air and collides with other air molecules

14
Q

what is tension?

A

the pulling force that a string or cable exerts when something or someone pulls in it

15
Q

what is friction?

A
  • when two surfaces are touching and try to move against each other.
16
Q

how does friction work?

A
  • Tiny bumps in the surface interlock (overlap or fit together). This creates a frictional force that opposes their motion.
17
Q

what kind of force is air resistance?

A

contact (air particles collide)

18
Q

what does a free body diagram show?

A

shows the forces acting on a single object

19
Q

what is a resultant force?

A

the force when two or more forces are added together

20
Q

what is a force?

A

a push of a pull

an attraction or repulsion

21
Q

what can a force do?

A
  • change the shape of an object

- change the motion of an object

22
Q

what are forces measured in?

A

N (newtons)

23
Q

state one way in which the force of gravity is different to the electrostatic force

A
  • gravity can only attract

- electrostatic force can attract and repel

24
Q

what happens when bodies interact?

A
  • exert forces upon each other
25
Q

what does a free body diagram show?

A

all the forces acting on a single body

26
Q

what does it mean to resolve a force?

A
  • work out how much of it acts in the horizontal plane

- work out how much of it acts in the vertical plane

27
Q

what is Newton’s First Law?

A

“A body will remain at rest, or continue to move at a uniform velocity, unless acted upon by a resultant force”.

28
Q

what is Inertia?

A

A measure of how difficult it is to change the velocity of a body (either from rest or when traveling at a uniform velocity)

29
Q

if an object has a higher mass, why does it have a higher inertia?

A
  • more difficult to accelerate/change velocity
30
Q

what is componenticing?

A

seeing how much force is acting on specific planes

31
Q

what is the equation for force?

A

F = M x A

newton’s second law

32
Q

what is the unit for acceleration?

A

m/s^2

meters per second squared

33
Q

define acceleration

A

the rate of change of velocity of a body

34
Q

if a body is travelling at a constant speed but a different direction, is it accelerating?

A

yes, as the velocity changes

35
Q

what is the equation for acceleration?

A

final velocity - initial velocity / time

36
Q

what does acceleration depend on?

A
  • size of resultant force

- inertia (mass) of object

37
Q

what stays the same during circular motion?

A
  • speed of the plane stays the same
38
Q

what changes during circular motion?

A

velocity continuously changes (direction)

39
Q

why is an object in circular motion continuously accelerating?

A

as it is constantly changing direction

40
Q

where does the centripetal force act?

A

towards the centre of the circle

41
Q

what does centripetal force change?

A
  • the direction of velocity

- NOT SIZE

42
Q

what is free fall?

A

the fall of a body through a medium, without a drag producing device

43
Q

explain why terminal velocity is a constant

A

the weight of the body is balanced by the drag force acting upon it

44
Q

which planes are considered for a box on a slope?

A
  • parallel to slope (where box tries to accelerate)

- perpendicular (where normal reaction force acts)

45
Q

what is the equation for momentum?

A

mass x velocity

46
Q

what is momentum a measure of?

A

how difficult it is to stop a moving body

47
Q

what is momentum measured in?

A

kgm/s (kilograms meters per second)

48
Q

what does momentum depend on?

A
  • mass

- velocity

49
Q

is momentum vector or scalar

A

vector (has direction)

50
Q

what is the law of conservation of momentum?

A

the movement before is equal to the momentum afterwards

51
Q

what is an inelastic collision?

A

when energy is transferred to other sources

52
Q

what is an elastic collision?

A

when no net energy is transferred to other sources (which is not kinetic energy)

ie. no energy lost as sound, light

53
Q

what happens when a stationary body is hit by a moving body

A

two bodies move off together

54
Q

what is the opposite force to the force of the Earth on a skateboarder

A

normal reaction force

force of skateboarder on earth

55
Q

what happens when two bodies push off each other?

A

bodies move away from each other

56
Q

what is work?

A

the transfer of energy

57
Q

what is work measured in

A

J (joules)

58
Q

what happens when work is done?

A

energy is transferred from one form to another

59
Q

what happens when you lift a body?

A

kinetic energy is transferred to gravitational potential energy

60
Q

what is the equation to calculate work done?

A

force x distance

61
Q

how much is one joule in newton meters?

A

1J = 1Nm

62
Q

what do we assume about distance?

A

it is covered at a constant velocity
(zero acceleration)
(zero resultant force)

63
Q

how does friction transfer energy?

A

out of a body (and transfers heat)

64
Q

what is power?

A

rate of transfer of energy

65
Q

how does a force applied transfer energy?

A

into a body

66
Q

what is the equation for power

A

energy / time

67
Q

what is power measured in?

A

Watts(W)

68
Q

how much energy is transferred during 1 watt (per second)

A

1 joule per second

69
Q

how is acceleration proportional to mass?

A

inversely proportional

70
Q

what is Newton’s Second Law?

A

“The acceleration experienced by a body is directly proportional to the resultant force acting upon it, and in the same direction”
AKA
‘push something harder, accelerate faster’