our Dynamic Universe

Question 1

Scalar quantities are described by

Answer 1

Magnitude only

Question 2

Vector quantities are described by

Answer 2

Magnitude and direction only

Question 3

Area below a velocity time graph is

Answer 3

Distance travelled

Question 4

Initially at rest

Answer 4

U=0

Question 5

Comes to a stop

Answer 5

V=0

Question 6

Reaches maximum height

Answer 6

V=0

Question 7

Accelerates due to gravity

Answer 7

A=9.8ms-1 downwards

Question 8

Gradient of a displacement time graph?

Answer 8

Velocity

Question 9

Gradient or a velocity time graph

Answer 9

Acceleration

Question 10

Friction is

Answer 10

The force between two surfaces that opposes motion

Question 11

The direction of friction is

Answer 11

Always in the opposite direction to the motion of an object

Question 12

At rest means

Answer 12

No acceleration and forces are balanced

Question 13

Constance velocity means

Answer 13

No acceleration therefore forced are balanced

Question 14

The upward force of air resistance increases with

Answer 14

Downward force of velocity

Question 15

Any vector quantity can be resolved into

Answer 15

2 perpendicular components

Question 16

All moving objects have

Answer 16

Kinetic energy and momentum

Question 17

Momentum is conserved in a collision as long as

Answer 17

No external forces act

Question 18

If the collision is elastic

Answer 18

Total kinetic energy also conserved

Question 19

If kinetic energy is not conserved the collision is

Answer 19

Inelastic

Question 20

If two objects stick and collide

Answer 20

m1u1+m2u2=(m1+m2)v since velocity is the same

Question 21

During inelastic collisions, energy is lost due too

Answer 21

Noise, heat and deforming materials

Question 22

During explosions, what is conserved

Answer 22

Total momentum

Question 23

Explosions are always

Answer 23

Inelastic as energy is added to the objects

Question 24

Momentum equals

Answer 24

Mass times initial speed

Question 25

Force times time equals

Answer 25

Change In momentum m1v1-m1u1

Question 26

If force is constant, force times time equals

Answer 26

The area or the rectangle, impulse is the area below the force time graph

Question 27

If force varies by time, impulse is the

Answer 27

Average force times time

Question 28

The horizontal component of a projectile is

Answer 28

Constant velocity (we ignore air resistance)

Question 29

The vertical component of a projectile is

Answer 29

Constance acceleration downwards true to gravity, equations of motion apply

Question 30

If an object is orbiting around a planet, it is in

Answer 30

Free fall

Question 31

What are Einstein’s postulates

Answer 31

The speed of light is the same for all observers The laws of physics are the same in different frames of reference.

Question 32

T’ is

Answer 32

Dilated time

Question 33

Is dilated time (t’) bigger or smaller than proper time (t)

Answer 33

Bigger

Question 34

L’ is the

Answer 34

Contracted length

Question 35

What is bigger, contracted lenght (l’) or proper length (l)

Answer 35

Proper lenght

Question 36

As the sound source move closer,

Answer 36

Waves closer together so frequency higher

Question 37

As the sound source moves away

Answer 37

Waves further apart so frequency lowers

Question 38

If the source is moving towards the observer

Answer 38

Subtract on the bottom line

Question 39

If the source is moving away from the observer

Answer 39

Add on the bottom line

Question 40

Light sources move away from us. Wavelength is increased this is called

Answer 40

Redshift

Question 41

A light source moving towards us would be

Answer 41

Blueshifted

Question 42

z

Answer 42

Redshift (no units)

Question 43

The universe is

Answer 43

Moving apart

Question 44

Dark matter

Answer 44

Energy that should be there but isn’t

Question 45

Dark energy

Answer 45

Energy that increases the rate of the expansion of the universe

Question 46

Hot objects emit radiation across a

Answer 46

Broad range of wavelengths

Question 47

As surface temperature increases

Answer 47

More energy is emmited and the peak in the distribution is shorter wavelengths

Question 48

Hubbles law evidence for expanding universe

Answer 48

Hubbles law suggests that universe began in same point 14 billion years ago and it is travelling in all directions outwards

Question 49

Olbers paradox

Answer 49

The night sky is dari apart from points of light, if the universe was infinite, everything would be light

Question 50

Cosmic microwave background radiation

Answer 50

Some of the energy in the Big Bang formed electromagnetic radiation, we can still obverse this radiation from all directions today.