Flashcards in Physics 5 Deck (62)

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1

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

### Friction

2

## How can friction be reduced

###
-Using rollers or wheels

- Having a smooth surface

3

## What are the types of forces

###
-friction

-weight (gravity)

-upthrust

-magnetic

-electrostatic

-nuclear

-thrust

4

## In what unit are forces measured

### N -> newtons

5

##
Air resistance and water resistance are forms of....

### Drag

6

## When does the drag force increase?

### When speed increases

7

## Top speed

### The maximum speed a object can go

8

## Energy stores

###
-kinetic

-chemical

-thermal

-gravitational potential

-elastic potential

-sound

9

## Law of conservation of energy

### Energy is never created or destroyed only transferred or stored

10

## Equation of speed

###
Speed= distance

—————–

time

11

## Mean (average) speed

###
total distance

———————

total time taken

12

## steep line on distance-time graphs

### Means you are travelling quickly

13

## Horizontal line on distance-time graph

### Not moving at all

14

## Relative speed

###
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

15

## Moment equation

###
Moment of the force = force x perpendicular distance from pivot

(N m) (N) (m)

16

## Lever

### A lever is a long bar that turns around the pivot

17

## Pivot

### The point where the object turns

18

## Synonym for pivot

### Fulcrum

19

## Rule to move load

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

20

## What does the lever do

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

21

## In equilibrium

### When the forces are balanced

22

## What are most machines used for

### Use smaller force to move a object

23

## Name 3 simple machines

###
-lever

-ramp

-pulley

24

## Why are Ramos efficient

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

25

## When is Less force needed in a ramp

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

26

## Pulley rule

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

27

## What does work mean

### The amount of energy transferred when a force moves something

28

## Formula to calculate work

###
Work done = force x distance moved

(J) (N) (m)

29

## What is a force field

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

30

## What are magnetic fields

### The space around a magnet where it can attract magnetic materials

31

## How can you find the shape of a magnetic fiel

### Using iron fillings

32

## Which objects have a gravitational field

### All objects with a mass have a gravitational field

33

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

### They attract each other

34

## What is the earths gravity

### ~ 10N/kg

35

## Equation for weight

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

36

## What kind of forces are there

###
-magnetic fields

-gravitational fields

37

## When can static electricity build up?

### When two different materials rub together

38

## What do atoms consist of

###
-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

## What happens when you rub two insulating materials together

### Some electrons may be transferred from one object to the other

40

## Can the positive charges be tranfered

### Because they are fixed to the nuclei of the atom

41

## What happens to the object that ends up with more electrons

### It has a overall positive charge

42

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

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

43

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

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

44

## What can attract uncharged objects

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

45

## What is the electric field

### The space around a charged object.

46

## When is the field stronger

### When it's closer to the object

47

## What is a electric current

### The flow of electrons, which are negatively charged particles

48

## Series circuit: does the current vary?

### No

49

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

### Yes

50

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

### The current is reduced and the bulbs get dimmer

51

## Parallel circuit: is the current always the same

### The current separates throughout the circuit because of junctions

52

## Parallel circuit: how are the bulbs controlled

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

53

## Parallel circuit: what happens if you add more bulbs

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

54

## How do we measure current

### With a ammeter (amps)

55

## How do we measure the voltage

### Using a voltmeter (volts)

56

## What is resistance

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

57

## Factors that affect resistance

###
-the longer the wire the higher the resistance

-the thicker the wire the higher the resistance

-insulators have a very high resistance

58

## What are the units for for resistance

### ohms

59

## How do you calculate voltage

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

60

## What is a electromagnet

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

61

## How do you increase the strength of a electro magnet

###
-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