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Science F2 > Chap 8 > Flashcards

Chap 8 Flashcards

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1
Q

what is force

A

force is a pull or a push upon an object

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2
Q

Force may exist in various forms/types such as :

A

gravitational force
weight
normal force
frictional force
elastic force
buoyant force

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3
Q

Explain gravitational force

A

-the force that points towards the centre of the earth
-causes all object that r thrown upwards to fall back to earth

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4
Q

explain normal force

A

-force produced when an object is in contact w a surface

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5
Q

explain weight

A
  • defined as the gravitational force acting on it
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6
Q

explain elastic force

A
  • exists when a material is stretched or compressed
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7
Q

explain buoyant force

A
  • the thrust force acting on an object that is floating on the surface of a fluid
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8
Q

explain frictional force

A
  • the force that resists movement between two surfaces that r in contact w each other
    -acts in the opposite direction of the motion
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9
Q

Characteristic of force

A
  • is a vector quantity that has magnitude n direction
    -has point of application
    -magnitude is the quantity or value of a measuremt
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10
Q

S.I. unit of force

A

Newton (N)

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11
Q

How do we measure force

A
  • using a spring balance
  • spring balance operates based on the principle of spring extension
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12
Q

100g has a weight of _____ N
1kg has a weight of ____ N

A

1 N
10N

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13
Q

Newtons third law states:

A

that for every action force, there is a reaction force of the same magnitude but in the opposite direction

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14
Q

Force cannot be seen but

A

its effects can be felt

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15
Q

force can change the:

A

shape, size and motion of the object

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16
Q

state the effects of force

A

-moving stationary object
- stopping a moving object
- changing the speed of an object that is in motion
-changing the direction of motion of an object
-changing the shape and size of an object

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17
Q

Explain buoyant force

A

-object will only float if the buoyant force acting on it is enough to support its weight
-will submerge if not enough

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18
Q

Actual weight means

A

weight of an object in the air

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19
Q

apparent weight means

A

weight of an object immersed in fluid

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20
Q

Explain how does an object float in fluid

A

-buoyant force pushes the object up to the surface bcuz the object is less dense than the liquid is when in the liquid

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21
Q

Why are cargo ships marked with plimsoll lines

A
  • for safety purposes
  • density of sea water is diff in diff parts of the world cuz of the temp and concentration in salt
  • plimsoll lines will help to determine the safe level for a ship to stay afloat
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22
Q

what is a lever

A

a bar that rotates on a fixed point

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23
Q

lever is made up of 3 parts, which are:

A
  • Effort
  • Load
  • fulcrum
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24
Q

Explain the 3 parts of a lever

A

Effort: force applied on the bar
Load: Object to be moved
Fulcrum: Fixed support point

25
Q

Explain purposes of lever

A
  • allows us to do work easily
  • allows us to use minimal force to do work
26
Q

levers are classified into 3 types:

A

-first class
-second class
-third class

27
Q

When does a lever classify as a first class lever

A
  • fulcrum is between lad and effort
28
Q

when does a lever classify as a second class lever

A

-load is between fulcrum and effort

29
Q

when does a lever classify as a third class lever

A
  • effort is between fulcrum and load
30
Q

WHat does moment of force mean

A
  • the turning effect produced when a force acting on an object can rotate the object at a fixed point
31
Q

Elaborate more abt moment of force:

A
  • allows us to do work easily
  • depends on the force applied & the perpendicular distance of the fulcrum to the force
32
Q

Force is always towards:

A

where we pull

33
Q

Method to calculate force:

A

Moment of force = Force (N) x perpendicular distance from the pivot to the force (m)

Simplified: MOF= (N x M)

34
Q

Unit for moment of force is

A

newton metre ( N m)

35
Q

moment of force has 2 directions

A
  • either clockwise or anticlockwise
36
Q

moment of force will increase if:

A
  • magnitude of force increases, by applying a greater force
  • perpendicular distance from pivot to effort increases
37
Q

Greater moment of force is produced when:

A

force is applied at a greater distance from the turning point

38
Q

Formula to solve daily life problems involving levers

A

Load (N) x Distance of load from fulcrum (m) = Effort (N) x Distance of effort from fulcrum (m)

simplified: N x distance of load (m) = N x distance of effort (m)

39
Q

S.I unit for pressure

A

pascal (Pa)

40
Q

1 Pa equals

A

1 newton per square metre ( N m-² )

41
Q

Pressure =

A

Force (N) / Surface area (m²)

42
Q

The smaller the _______, the _______ it is for that thing to be pressed

A

-surface area
-easier

43
Q

pressure defined as

A

force per unit area

44
Q

Kinetic theory of gas states:

A

air molecules always move about freely and collide with the walls of its container

45
Q

Whats air pressure

A
  • the force that pushes against the walls and is produced as a result of the frequency of collision between the air molecules and the walls of the container
46
Q

Factors that affect air pressure

A

-volume
-temp

47
Q

what happens when a close container is compressed

A

-volume in the container is reduced
- causes the air particles to collide more frequently w the walls of the container
- air pressure in the container increases

48
Q

What happens when air temp in a closed container increases

A
  • air particles move faster
  • causes air particles to collide w the walls of container more frequently and w a greater force
    -air pressure increases
49
Q

the lower the temp, the ____ the movement of air particles

A

-slower

50
Q

the higher the temp, the ___ the movement of air particles

A
  • faster
51
Q

What causes a packet to compress when drink is sucked out

A
  • the drink inside becomes a partial vacuum
    -air pressure inside decreases
    -the higher the air pressure outside will press onto the packet and compress it
52
Q

what is the air pressure outside called

A

atmospheric pressure ( aka the pressure exerted by the atmosphere on the surface n all objects on earth )

53
Q

examples of application of the concept of air pressure in daily life

A

-plunger
-magdeburg hemisphere
-straw
-syphon
-syringe
-vacuum cleaner

54
Q

atmospheric pressure ____ as altitude increases

A

-decreases

55
Q

Explain gravitational attraction

A
  • air molecules closer to the surface of the earth r pulled tgt by the gravitational attraction causing a rise in pressure
  • at higher altitudes, air molecules are less affected by the gravitational attraction, so air becomes less heavy n expands easily
    -causes a low atmospheric pressure at high altitude
56
Q

Liquid pressure decreases as the:

A

depth of liquid decreases

57
Q

Liquid has more pressure at the _

A

bottom

58
Q
A

Science F2 (13 decks)

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