Hsc Physics (Aus)

Front 1

Mass (Kg) vs Weight (N)

Back 1

Weight is a force on an object that is in a gravitational field where as
Mass is the amount of matter in an object.

Front 2

F = ma

Back 2

where;
F = force
m = mass (Kg)
a = acceleration (m/s)

Front 3

Gravitational Field

Back 3

- shows the direction a smaller mass would move if placed near a large mass
- field lines point towards a massive object
- On Earth's surface the gravitational field lines are uniform

Front 4

W = mg

Back 4

where;
W = weight in N
m = mass in kg
g = acceleration due to gravity (9.8m/s-⒉ on Earth)

Front 5

Factors affecting acceleration due to gravity (g)

Back 5

- Height, as height increases g decreases
- Density, points of higher density will also have slightly higher g
- Mass/Radius, larger mass and smaller radius will have a larger g

Front 6

Newtons Law of Universal Gravitation

Back 6

- Any object that has mass, has gravity
- Larger objects have stronger gravitational fields thus more noticeable gravity

Front 7

Magnitude of Gravitational attraction, where:
G = universal gravitational constant
m = mass (kg)
r = distance from centres (m)
F = force (N)

Back 7

F = G m① x m②
----------- r⒉

Front 8

Gravitational Potential Energy (GPE)

Back 8

The work done to move an object from a very large distance away to a point in a gravitational field
- GPE is ALWAYS negative
- If we raise and object, it gets more GPE

Front 9

E*p = - G m① x m②
----------------- r

Back 9

where;
E*p = potential energy (J) [Joules]
G = universal gravitational constant
m = mass (Kg)
r = distance from centres (m)

Front 10

GPE at infinity distance away from any gravitational field.

Back 10

- Has a GPE of 0 joules/ is no longer in a gravitational field
- Brought closer than infinity away it has less than o GPE but is now in a gravitational field

Front 11

Projectile Motion

Back 11

- Follows a parabolic path.
- Can be split into vertical and horizontal components.
- Vertical velocity at the peak is 0 m/s
-Horizontal velocity stays constant (V = u)

Front 12

Equations for Projectile Motion
where;
s = displacement
u = initial velocity
V = final velocity
a = acceleration
t = time

Back 12

V⒉= u⒉ + 2as
s = ut + ½ a t⒉
v = u + a t

Front 13

Range and Launch Angle

Back 13

- At 45∘ a projectile will achieve it's maximum range.
- an angle of < 45∘ will give a projectile more horizontal velocity but less time in the air (because it doesn't have the height)
- an angle of > 45∘ will give a projectile more time in the air, but less horizontal velocity

Front 14

.The velocity at which an object on the surface of a body must be propelled in order not to return to that body under the influence of their mutual gravitational attraction

Back 14

Escape Velocity - definition

Front 15

Escape Velocity

V*e = √ ( 2G m*planet
------------- r*planet )

Back 15

- Does not depend upon the mass of the object trying to escape
- Newton's idea for escape velocity came from projective motion

Front 16

G - forces

Back 16

a persons apparent weight as a multiple of their true weight

Hint 16

- experienced when a person accelerates (changes velocity)

Front 17

Human limitations in relation to G-forces.

Back 17

A person can withstand between ~ ≤10 g
(this causes blood to rush towards the feet and the person may black out)

Hint 17

and ≥ -3 g
(this causes the blood to rush to the head and burst a capillary causing bleeding to the brain)

Front 18

Rockets are launched:

Back 18

with the rotation of the Earth so they have the additional rotational velocity.

Front 19

Uniform Circular Motion

Back 19

is circular motion with a constant speed.

Hint 19

a*c = v⒉
-------- r

Front 20

Centripetal force

Back 20

always acts towards the centre of the circle.

Hint 20

F*c = mv⒉
--------- r

Front 21

Kepler's law of periods

Back 21

r⒊ = Gm
T⒉ 4π⒉
Calculates orbital velocities

Hint 21

- Period is in seconds,
- radius in metres and
- radius is the distance between the centres of the object in orbit and the heavenly body it is orbiting
(altitudes needs the radius added to it)

Front 22

Elliptical orbits are _ shaped

Back 22

oval

Front 23

Satellites in a low Earth orbit; (LEO) - [higher than 250km, lower than 1000km]

Back 23

move fast and can slow down due to atmospheric drag and crash to Earth

Front 24

Satellites in a Geostationary orbit;
(where the period of the satellite is 24hrs)

Back 24

remain above the same position relative to the Earth's surface

Front 25

If the angle of re-entry is too high __

Back 25

a spacecraft will burn up due to the heat produce on re-entry

Front 26

If the angle of re-entry is too low __

Back 26

the spacecraft will 'skip' or bounce off the atmosphere and back into space and may not have enough fuel to re-enter again.

Front 27

Ionisation Blackout occurs during re-entry, it is __

Back 27

a period where no radio communication occurs because of ionised particles around the shuttle

Hint 27

The heat from re-entry ionises the air particles around the spacecraft.

Front 28

G-forces can be problematic for astronauts during re-entry, if the angle of entry is more vertical then __

Back 28

the deceleration is greater and the g-forces experienced are also greater.

Front 29

The sling shot effect is a manoeuvre designed to __

Back 29

increase or decrease the velocity of a satellite or spacecraft.
- the satellite gets dragged by the planets orbital motion

Hint 29

The satellite goes behind the planet to increase velocity
and in front of the planet to decrease velocity

Front 30

An inertial frame of reference is __

Back 30

a frame of reference that is in constant motion or stationary

Hint 30

it is impossible to distinguish between a stationary frame of reference and a frame of reference in constant motion without obseving another frame of reference

Front 31

A non-inertial frame of reference is __

Back 31

a frame of reference that is not in constant motion or stationary (i.e it is accelerating)

Front 32

If you are on a moving platform and throw a tennis ball forward, the tennis ball will have the throwing speed plus the platform speed as observed by a stationary observer.

Back 32

You observe the tennis ball move at only the throwing speed because you are in motion with it.

Hint 32

This is Newtonian relativity (but light doesn't conform to it - light is a hipster)

Front 33

The Aether Model states that the properties of the aether are:

Back 33

* It was the medium that light propagated through*
- The aether filled all of space
- It has a low density
- It was perfectly transparent
- it was perfectly non viscous
- It was very stiff, allowing light to travel very fast through it

Front 34

Michelson - Morley Experiment
aimed to _

Back 34

find the relative motion of the aether.
They did this by racing two light beams, one with the aether and one across at 90∘ to the aether.

Hint 34

When the two light beams met at the interferometre if they were out of phase then the light would destructively interfere, if in phase they would constructively interfere.
- The experiment found that there was no relative motion of the Earth to the aether.

Front 35

Einstein's theory of light states that __

Back 35

- Light travels at the same speed in all frames of reference.
- Light does not need a medium to travel through, it is self propagating.
- If light travels at the same speed in all frames of reference then distance and time will be different in both frames of reference.

Front 36

Relativity of simultaneity states that __

Back 36

- Simultaneous eventsin one frame of reference are not necessarily simultaneous in another frame of reference.
also

Hint 36

- Both observers are correct in their observations (even if their observations seen contradictory)

Front 37

In a moving frame of reference, time dilates - equation

Back 37

t*v = t*o
----- √ 1-(v⒉/c⒉)

Front 38

In a moving frame of reference, time:

Back 38

- appears to run as normal as seen from this frame of reference
- on Earth time runs faster as seen from this frame of reference

Front 39

In a stationary frame of reference, time:

Back 39

- appears to run as normal as seen from this frame of reference
- in a moving object runs slower as seen from this frame of reference

Front 40

Experiment to test the relativity of time:

Back 40

Two atomic clocks are syncronised, one remains stationary while the other is placed in a high speed jet. The atomic clock in the jet travels at high speeds for a period of time and brought back to rest. The two atomic clocks are compared and the one that was in the high speed jet has 'lost time'.

Front 41

The length of a moving object contracts (it gets shorter) - equation

Back 41

ℓ*v = ℓ*o √ [1-(v⒉/c⒉)

Front 42

In a moving frame of reference, length:

Back 42

- appears as normal as seen from this frame of reference
- length of the Earth is shorter as seen from this frame of reference

Front 43

In a stationary frame of reference, length:

Back 43

- appears as normal as seen from this frame of reference
- length of a moving object is shorter as seen from this frame of reference

Hint 43

No experiment to test this as of yet.

Front 44

The mass of a moving object dilated (it gets heavier) - equation

Back 44

m*v = m*o
----- √ 1-(v⒉/c⒉)

Front 45

Experiment to test relativity of mass:

Back 45

Beta particles (electrons) that are emitted from a radioactive source travel at speeds of near the speed of light.
Results:

Hint 45

When the q to m ratio of these beta particles is measured it is different to that of a slower electron. When the beta particles speed is factored into the equation it's q to m ratio is the same as other electrons.

Front 46

Relativity of simultaneity states that __

Back 46

- Simultaneous eventsin one frame of reference are not necessarily simultaneous in another frame of reference.
also

Hint 46

- Both observers are correct in their observations (even if their observations seen contradictory)

Front 47

In a moving frame of reference, time dilates - equation

Back 47

t*v = t*o
----- √ 1-(v⒉/c⒉)

Front 48

In a moving frame of reference, time:

Back 48

- appears to run as normal as seen from this frame of reference
- on Earth time runs faster as seen from this frame of reference

Front 49

In a stationary frame of reference, time:

Back 49

- appears to run as normal as seen from this frame of reference
- in a moving object runs slower as seen from this frame of reference

Front 50

Experiment to test the relativity of time:

Back 50

Two atomic clocks are syncronised, one remains stationary while the other is placed in a high speed jet. The atomic clock in the jet travels at high speeds for a period of time and brought back to rest. The two atomic clocks are compared and the one that was in the high speed jet has 'lost time'.

Front 51

The length of a moving object contracts (it gets shorter) - equation

Back 51

ℓ*v = ℓ*o √ [1-(v⒉/c⒉)

Front 52

In a moving frame of reference, length:

Back 52

- appears as normal as seen from this frame of reference
- length of the Earth is shorter as seen from this frame of reference

Front 53

In a stationary frame of reference, length:

Back 53

- appears as normal as seen from this frame of reference
- length of a moving object is shorter as seen from this frame of reference

Hint 53

No experiment to test this as of yet.

Front 54

The mass of a moving object dilated (it gets heavier) - equation

Back 54

m*v = m*o
----- √ 1-(v⒉/c⒉)

Front 55

Experiment to test relativity of mass:

Back 55

Beta particles (electrons) that are emitted from a radioactive source travel at speeds of near the speed of light.
Results:

Hint 55

When the q to m ratio of these beta particles is measured it is different to that of a slower electron. When the beta particles speed is factored into the equation it's q to m ratio is the same as other electrons.

Front 56

E = mc⒉
As an object is accelerated some of the __ (work) used to accelerate it is changed into __ this is why it is impossible to go faster than the speed of light (__), because you can't put in infinite __ to accelerate an object of infinite __.

Back 56

energy, mass, (3x10⒏m.s-⒈), energy, mass.
- If mass is destroyed as it is in a nuclear explosion, that mass is changed into __.

Hint 56

energy.

Front 57

The Twins Paradox says that when two twins, one stationary and one moves away at near the speed of light and comes back - what happens?

Back 57

The moving twin is younger, than the stationary twin that remains on Earth.
If we observe this situation from the moving twin's frame of reference, s/he is __ and the twin that remains on Earth is __ so the aging effects should be __ but it is not.
- why?

Hint 57

stationary, moving, reversed
This is because one is in an inertial frame of reference (the stationary twin) the other is in a non-inertial frame of reference (not constant speed)(the moving twin).

Front 58

Magnetic field lines go from __ to __.
The number of field lines represents the __ of the magnet.
(x) represents __ the page ⨀ represents __ of the page.

Back 58

north, south,
strength,
into, out

Front 59

Magnetic field lines never cross, except __

Back 59

in a galvanometre (radical magnetic field).

Front 60

The magnetic field around a current carrying conductor is found by the __

Back 60

right hand grip rule (thumb points in the direction of conventional current).

Front 61

Conventional current flows from _ to _.
Electrons flow from _ to _.

Back 61

'+' (positive) '-' (negative)
'-' (negative) '+' (positive)

Front 62

A solenoid is __

Back 62

a coil of wire that makes a magnetic field (more coils, stronger field).

Front 63

The motor effect

Back 63

When a current is placed in a magnetic field it will experience a force.

Front 64

The direction a current carrying conductor will move when place in a magnetic field can be determined by __

Back 64

the right hand palm rule.
Where:
thumb indicates __
fingers show __
palm moves __

Hint 64

direction of conventional current (I).
magnetic field lines (B).
in the direction of the force it experiences (F).

Front 65

Factors that affect the magnitude of the force on a current carrying conductor are:

Back 65

- Strength of the magnetic field.
- Amount of current flowing through wire
- Angle between conductor and magnetic field (elaborate)
- Length of the conductor

Hint 65

If the angle of the wire is parallel to the field lines then the force experienced is zero.
If the wire is at 90∘ to the field lines then the force it experiences is a maximum.

Front 66

Calculate force using equation -

Back 66

F = B I ℓ sinθ
where:

Hint 66

F = force (N)
B = magnetic field strength (T)
I = current (A)
ℓ = length of the conductor in magnetic field (m)
θ = angle between conductor and the field lines (∘)

Front 67

Parallel wires that have current flowing in the __ direction will attract.
Parallel wires that have current flowing in the __ direction will repel.

Back 67

same
opposite

Front 68

Factors that affect the force on parallel conductors:
F = k x I①x I②
ℓ ---- d

Back 68

F = force on wire (N)
ℓ = parallel length of conductors (m)
k = 2x10-⒎ magnetic force constant
I① = current through wire ①
I② =current through wire ②
d = distance between wires (m)

Front 69

The main parts of a DC motor are:

Back 69

Stator - the stationary part of the motor (usually the magnets)
Rotor - the rotating part of the motor (usually the coil)
Split Ring Commutator - a ring that allows the current to be reversed
Brushes - allows contact from the power to the commutator

Front 70

Torque is __

Back 70

a turning force.
t = Fd
t = torque (N.m)
F = force (N)
d = distance (m)

Front 71

Calculating torque in a motor equation -

Back 71

t = nBIAcosθ
where:

Hint 71

t = torque
n = number of coils
B = magnetic field strength (T)
I = current (A)
A = area of the coil (m⒉)
θ = angle relative to magnetic field

Front 72

When a conductor is moved relative to a magnetic field __

Back 72

then an electric current is produced.

Front 73

Magnetic flux is __

Back 73

a measure of the amount of magnetic field permeating a space - measured in weber (Wb)

Front 74

Magnetic flux density is __

Back 74

the amount of magnetic flux passing through a square metre - measured in tesla (T) - also known as magnetic field strength

Front 75

- magnetic flux = flux density x area
- flux density = magnetic flux/area

Back 75

ɸ = BA
B = ɸ/ A

Front 76

An eddy current is a __ current induced in a conductor that is in a __ magnetic field. The direction of the eddy current can be determined using the ___.

Back 76

circular
changing
right hand grip rule

Front 77

Eddy currents need a ___. If there is no ___ then their size is restricted.

Back 77

connecting pathway

Front 78

__ motors have a ___ commutator, allowing the direction of the current to be changed so that the motor can continue to spin.
__ motors have a ___ commutator because the direction of the current is already changing so it doesn't need to be changed.

Back 78

DC, split ring
AC, slip ring

Front 79

A generator uses __ energy to make __ energy. A motor is the same in structure as a generator but __ in what we do with it.

Back 79

kinetic
electrical
opposite

Front 80

Transformers are:

Back 80

devices that increases or decreases AC voltages
Consisting of:

Hint 80

a primary coil and a secondary coil wound onto a soft iron core.

Front 81

To calculate primary and secondary voltage equation -

Back 81

-- V(primary) = n(primary)
V(secondary) n(secondary)
where:
V = voltage
n = number of coils

Front 82

High current means __ energy changed into heat.
Low current means __ energy changed into heat.

Back 82

more
less

Front 83

Step Up Transformers make output voltage __ than the input voltage.
Step Down Transformers make output voltages __ than the input voltage.

Back 83

greater
less
- explain the use of each

Hint 83

Step up used to transmit electricity across large distances so energy loss is minimised.
Step down used to run in houses for most appliances.

Front 84

Like DC motors, DC generators and AC generators, AC motors are made with a __ and a __.
Most AC motors use a ___ commutator and have a ___ rotor that rotates around the axis of the shaft.

Back 84

rotor, stator, slip ring, cylindrical.
*The slip rings used in AC motors (and generators) consists of two full rings which are __ connected to one end of the coil.
- What does this do to the direction of the current?

Hint 84

permanently.
*This ensures that as AC input changes, the direction of the current flow through the coil remains constant and so will the direction of the torque.

Front 85

How does an induction motor work?

Back 85

By using a changing magnetic field to induce a current in the rotor.

Front 86

A ____ consists of a number of conducting bars joined together by 'end rings'

Back 86

'squirrel cage'