Forces Flashcards
1
Q
Define physical quantity
A
A physical quantity is a physical property of a phenomenon, body, or substance, which
can be quantified by measurement.
2
Q
Quantity symbol of time
A
t
3
Q
Quantity symbol of mass
A
m
4
Q
Quantity symbol of force
A
F
5
Q
Quantity symbol of weight
A
Fg
6
Q
Quantity symbol of charge
A
Q
7
Q
Si unit for seconds (t)
A
s
8
Q
Si unit for kilograms (m)
A
kg
9
Q
Si unit for newton (F)
A
N
10
Q
Si unit for newton (Fg)
A
N
11
Q
Si unit for coulomb (Q)
A
C
12
Q
What two groups are classified as physical quantities
A
Scalar quantities
Vector quantities
13
Q
Define Scalar quantity
A
A scalar quantity is a physical quantity that has
magnitude (size) only.
14
Q
What does scalar quantity include?
A
Mass, electric charge, time, distance (MEDT) scales of fish
15
Q
Define vector quantity
A
A vector quantity is a physical quantity that has
magnitude and direction.
16
Q
What does vector quantity include?
A
Force, weight, velocity, acceleration (WAVF)
17
Q
What are the two ways of describing direction?
A
Relative direction and compass points
18
Q
What is relative direction?
A
up, down, left, right, forwards, backwards
19
Q
What is compass points?
A
North, east, south, west
20
Q
How is a vector shown?
A
arrow pointing to the right written above it
21
Q
When is arrow left out of vector?
A
If the magnitude (size) of a vector is only needed, then the arrow is omitted (left out).
22
Q
How are vectors graphically represented?
A
Arrow defining the direction, and the length of
the arrow defines the vector’s magnitude according to a scale.
23
Q
How are two vectors equal?
A
Equal if they have the same magnitude and direction,
regardless of whether they have the same initial points,
24
Q
Define forces
A
A force is a push or a pull that acts in a certain
direction.
25
What two things do forces have?
Magnitude (size) and direction
26
What can forces change?
Change a body's state of motion in a straight line.
27
How can forces be measured?
spring scale/spring balance/newton meter (
28
What spring scales include?
Spring connected to a metal hook
29
When does the spring stretch (balance)?
Force is applied to hook
30
When does the spring stretch long?
The bigger the force applied, the longer
the spring stretches and the higher the reading.
31
When describing a force, which of the following 4 points must be noted?
exerting the force
experiencing the force
magnitude of the force
direction force is being exerted
32
What does the length of the arrow represent?
Represents the magnitude of the force
33
What does the arrowhead represent?
arrowhead represents the direction of the force.
34
How can we also describe the direction in which a force acts?
cardinal points system
35
What are free body diagrams are used to represent?
Free body diagrams are used to represent all of the forces acting on an object graphically.
36
What happens when more than one force can act on an object at a time?
Multiple arrows connected to the same dot.
37
If the forces are acting in the same direction, what do you do?
Draw separate arrows, connected to
the same dot
38
How does one represent force?
uppercase 'F' to show that it is a force,
subscript to show who or what is exerting the force.
39
What are the effects of forces?
Forces do not always have an effect, but the effects that they can have are the following.
40
Name the four effects of forces
Motion, distortion, direction, rotation
41
What is motion?
change the speed of an object.
cause a stationary object to move.
cause a moving object to stop.
42
What is distortion?
change the shape of an object.
Elastic objects return to their original shape - force removed.
Inelastic objects are permanently distorted.
43
What is direction?
A force can change the direction in which
something is moving.
44
What is rotation?
A force can cause an object to spin.
45
Define balanced and unbalanced forces
The resultant force (Fnet) is the single force which
has the same effect as the original forces acting
together.
46
What is another word for Fnet?
Resultant force
47
Fnet = 0
Balanced force
48
Fnet = 0 not
Unbalanced force
49
When does Fnet occur?
When multiple forces act on the same object
50
What are balanced forces?
Balanced forces have equal magnitudes but act in opposite directions.
51
Why is the resultant force zero (balanced)?
They cancel each other out and the overall effect is zero
52
When the forces are balanced, there is no change in the object's state of motion:
A stationary object remains stationary
A moving object keeps on moving at the same speed in the same direction
53
What are unbalanced forces?
do not have equal magnitudes
do not cancel each other
54
What effects do unbalanced forces have on?
overall effect on the body
55
How does one show forces graphically?
Head to tail diagrams
56
How does one calculate forces graphically?
Algebraically
57
What is the formula to determine the resultant force?
Fnet = F1 + F2
58
What formula must one use when calculating the resultant force acting in the same direction?
Fnet = F1 + F2
59
What formula must one use when calculating the resultant force not acting in the same direction?
Assign one direction positive - other negative
Fnet = F1 + F2
= + + (-)
60
When describing resultant force, what must one include?
Magnitude and direction
61
What do forces occur in?
Pairs
62
When forces occur in pairs, what is it called?
• Act on two different objects
• Have the same magnitude
• Act in opposite directions
63
Object A exerts force on object B
FA on B
64
Object B exerts force on object A
FB on A
65
Are moving forces balanced?
Forces are balanced when they are not moving
66
What are the two types of forces?
Contact and non-contact forces
67
Define contact forces
Results when interacting objects are touching. Physical contact
68
What does contact forces include?
Friction, tension, and compression
69
Which type of force is action reaction?
Contact forces
70
Define friction
The force that opposes the motion of an object and which acts parallel to the surface
71
Define tension
The stretching force that is exerted by a rope, string or wire when it is pulled by a force.
72
Define compression
The force that pushes or squeezes something into a smaller space.
73
Define non-contact forces
Act over a distance and occur when two interacting objects are not in physical contact with each other
74
What does non-contact forces include?
Magnetic, electrostatic and gravitational
75
What is another name for non-contact forces?
Field forces
76
What is magnetic force exerted by?
Any magnet
77
What is magnetic force experienced by?
Any magnetic material
78
What type of force is magnetic?
Attraction/Repulsion
79
What is electrostatic force exerted by?
Any charged object
80
What is electrostatic force experienced by?
any charged or neutral object
81
What type of force is electrostatic?
Attraction/Repulsion
82
What is gravitational force exerted by?
Any object with mass
83
What is gravitational force experienced by?
Any object with mass
84
What type of force is gravitational ?
Attraction
85
What is a magnetic force?
A magnetic force is a force that two magnetic materials exert on each other over a distance.
86
What do magnets attract?
Other magnetic materials
87
What material are magnetic substances?
Iron, cobalt, nickel
88
How many poles do magnets have?
All magnets have two poles: a north pole and a south pole.
89
Define magnetic fields
Regions in space around magnetic objects where magnetic force is experienced.
90
Which poles attract?
Opposite poles attract
91
Which poles do not attract?
like poles repel
92
What type of magnet is the earth?
The Earth can be considered as one large bar magnet,
with a south pole and a north pole.
93
Why will objects experience magnetic force?
The Earth has a magnetic field around it, therefore when placed within this field, objects will experience a magnetic force.
94
What is the magnetic north pole of a compass is attracted to?
The geographical North Pole of the Earth.
95
What is the North pole actually?
South pole of the Earth's magnet.
96
Define electrostatic force
An electrostatic force is a force that two electrically
charges objects exert on each other over a distance.
97
When does an electrostatic field exist?
An electrostatic field exists around any charged
object, and another object placed in that fields will
experience a force.
98
What happens when certain materials are rubbed together?
They can acquire an electrostatic charge as a result of
the loss or gain of electrons.
99
What has a gravitational field around it?
Any large object (planet, the sun, the moon)
100
What will experience gravitational attraction?
any object placed in that field will experience a force of attraction.
101
What does the magnitude of the gravitational force of attraction between two objects depends on?
The mass of the objects
The greater the distance
102
What does objects with a larger mass exert?
a greater force of attraction
103
What type of force does the greater the distance between the two objects create?
the smaller the force
104
What is gravity?
'Gravity' is the gravitational force of attraction that the Earth exerts on all objects.
105
Which direction does gravity act?
vertically downwards, towards the centre of the Earth.
106
What is gravity also called?
Weight
107
Define weight
Weight is the gravitational force that the Earth exerts on any object on or near its surface.
108
Is mass and weight the same thing?
No
109
Unit for weight
Newton
110
What does weight depend on?
Depends on where the object is (variable)
111
How is weight measured?
Measured using a spring scale/balance
112
Define mass
A measure of the quantity of matter possessed by an object
113
Unit for mass
Kilogram
114
What does mass depend on?
Constant regardless of where the object is
115
How is mass measured?
Measured using a triple beam balance
116
What do balances determine?
A balance determines mass by balancing an unknown mass against a known mass
117
How do scales determine weight?
Most weighing scales use sets of springs to measure the force acting on a mass to determine weight.
118
Formula for gravitational force
Fg = mg
119
What is the acceleration due to gravity for earth?
9,8
120
What is the acceleration due to gravity for moon?
1,6
