Physics 5 Flashcards

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1
Q

What force us created when a object is pulled along the ground?

A

Friction

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2
Q

How can friction be reduced

A
  • Using rollers or wheels

- Having a smooth surface

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3
Q

What are the types of forces

A
  • friction
  • weight (gravity)
  • upthrust
  • magnetic
  • electrostatic
  • nuclear
  • thrust
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4
Q

In what unit are forces measured

A

N -> newtons

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5
Q

Air resistance and water resistance are forms of….

A

Drag

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6
Q

When does the drag force increase?

A

When speed increases

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7
Q

Top speed

A

The maximum speed a object can go

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8
Q

Energy stores

A
  • kinetic
  • chemical
  • thermal
  • gravitational potential
  • elastic potential
  • sound
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9
Q

Law of conservation of energy

A

Energy is never created or destroyed only transferred or stored

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10
Q

Equation of speed

A

Speed= distance
—————–
time

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11
Q

Mean (average) speed

A

total distance
———————
total time taken

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12
Q

steep line on distance-time graphs

A

Means you are travelling quickly

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13
Q

Horizontal line on distance-time graph

A

Not moving at all

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14
Q

Relative speed

A

Add= if you are on a train and the train is moving at 50km/h and you move the same direction at 3km/h your relative speed is 53km/h
Subtract= if you are on a train which is moving at 50km/h and you move in the opposite direction at 3km/h your relative speed is 47km/h
Multiply=if two trains are traveling at 50km/h towards each other the are moving at a relative speed of 100km/h

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15
Q

Moment equation

A

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

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16
Q

Lever

A

A lever is a long bar that turns around the pivot

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17
Q

Pivot

A

The point where the object turns

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18
Q

Synonym for pivot

A

Fulcrum

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19
Q

Rule to move load

A

The longer the lever the easier it is to move the load

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20
Q

What does the lever do

A

Acts like a force multiplier if the effort distance is larger than the load distance

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21
Q

In equilibrium

A

When the forces are balanced

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22
Q

What are most machines used for

A

Use smaller force to move a object

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23
Q

Name 3 simple machines

A
  • lever
  • ramp
  • pulley
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24
Q

Why are Ramos efficient

A

It needs less force to push a object up a ramp than it does to lift it directly

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25
Q

When is Less force needed in a ramp

A

The shallower the slope the less force needed, but more distance to reach its height.

26
Q

Pulley rule

A

If the force is halved the distance the rope is has to be double

27
Q

What does work mean

A

The amount of energy transferred when a force moves something

28
Q

Formula to calculate work

A

Work done = force x distance moved

J) (N) (m

29
Q

What is a force field

A

A force field is a space where a non-contact force has a effect

30
Q

What are magnetic fields

A

The space around a magnet where it can attract magnetic materials

31
Q

How can you find the shape of a magnetic fiel

A

Using iron fillings

32
Q

Which objects have a gravitational field

A

All objects with a mass have a gravitational field

33
Q

What happens when objects are in each other’s gravitational field.

A

They attract each other

34
Q

What is the earths gravity

A

~ 10N/kg

35
Q

Equation for weight

A

Weight (N) = mass (kg) x g (N/kg)

36
Q

What kind of forces are there

A
  • magnetic fields

- gravitational fields

37
Q

When can static electricity build up?

A

When two different materials rub together

38
Q

What do atoms consist of

A
  • a central nucleus with small particles called electrons moving around it.
  • the nucleus has a positive charge and each electron has a negative charge.
  • this way they are balanced
  • the total positive and negative charges are usually the same.
39
Q

What happens when you rub two insulating materials together

A

Some electrons may be transferred from one object to the other

40
Q

Can the positive charges be tranfered

A

Because they are fixed to the nuclei of the atom

41
Q

What happens to the object that ends up with more electrons

A

It has a overall positive charge

42
Q

What happens when you rub a acetate rod with a piece of cloth

A

The acetate ends up with less negative electrons and has a overall positive charge, and the cloth has a overall negative charge.

43
Q

What happens when you rub a polythene rod with a piece of cloth

A

The negative electrons from the cloth move to the rod making the rod negative and the cloth positive.

44
Q

What can attract uncharged objects

A

Something with a charge of static electricity, it’s very small normally just notice it with small things (e.g hair)

45
Q

What is the electric field

A

The space around a charged object.

46
Q

When is the field stronger

A

When it’s closer to the object

47
Q

What is a electric current

A

The flow of electrons, which are negatively charged particles

48
Q

Series circuit: does the current vary?

A

No

49
Q

Series circuit: do all the bulbs go off when a switch is opened

A

Yes

50
Q

Series circuit: If you add more bulb to the circuit what will happen

A

The current is reduced and the bulbs get dimmer

51
Q

Parallel circuit: is the current always the same

A

The current separates throughout the circuit because of junctions

52
Q

Parallel circuit: how are the bulbs controlled

A

Each bulb is controlled individually (depending where the switch is placed)

53
Q

Parallel circuit: what happens if you add more bulbs

A

The bulbs all stay at their original brightness, the current trough each bulb stays the same.

54
Q

How do we measure current

A

With a ammeter (amps)

55
Q

How do we measure the voltage

A

Using a voltmeter (volts)

56
Q

What is resistance

A

A way of saying how easy or difficult it is for the current to flow through it.

57
Q

Factors that affect resistance

A
  • the longer the wire the higher the resistance
  • the thicker the wire the higher the resistance
  • insulators have a very high resistance
58
Q

What are the units for for resistance

A

ohms

59
Q

How do you calculate voltage

A

Voltage (V)= current (A) x resistance (ohms)

60
Q

What is a electromagnet

A

A wire with a electric current flowing that has a magnetic field

61
Q

How do you increase the strength of a electro magnet

A
  • increasing the number of coils around the wire.
  • increasing the current in the wire.
  • using a magnetic material as a ‘core’ inside the coil of wire.
62
Q

When does the direction of the magnetic change

A

When the current changes direction