P1 - The Universe

Question 0

Which states of matter does sound travel through the fastest and slowest?

Answer 0

Faster in solids than liquids

Faster in liquids than gases

Question 1

What causes sound waves?

Answer 1

Vibrating objects

Question 2

Which type of wave is sound?

Answer 2

Longitudinal

Question 3

Why do echoes happen?

Answer 3

They are reflected sound waves

Question 4

What else can sound waves do?

Answer 4

Diffract and refract

Question 5

What effect does changing the frequency of a sound wave?

Answer 5

The higher the frequency, the higher the pitch

Question 6

What effect does changing the amplitude of a sound wave have?

Answer 6

The higher the amplitude, the louder the sound

Question 7

How is the universe changing?

Answer 7

It is expanding and all galaxies are moving away from each other

Question 8

How do we know that the universe is expanding?

Answer 8

The light from other galaxies is red-shifted

Question 9

Describe red-shift

Answer 9

Different chemicals absorb different frequencies of light so each element produces a specific set of dark lines at the frequencies that it absorbs in the visible spectrum

The dark lines in light from distant galaxies are shifted towards the red side of the spectrum

This is red-shift

Question 10

What causes red-shift?

Answer 10

The doppler effect

Question 11

Describe the doppler effect

Answer 11

The frequency of a source moving towards you will seem higher so the wavelength will seem shorter and frequency will be higher

The opposite is true for an object moving away from you

Question 12

What type of wave does the doppler effect occur in?

Answer 12

Both transverse and longitudinal

Question 13

What effect does changing the distance to a galaxy have in red-shift and why?

Answer 13

The further away the galaxy, the greater the red-shift because galaxies further away are moving away from us faster than nearer ones

Question 14

What are the 2 theories for the origin of the universe?

Answer 14

Big bang theory

Steady state theory

Question 15

Describe the big bang theory

Answer 15

All matter and energy in the universe must have been compressed into a very small space and then it exploded from that point and started expanding

Question 16

Describe the steady state theory

Answer 16

The universe has always existed as it does now and always will do

The universe is expanding because matter is being created in the spaces as the universe expands

Question 17

Why is the big bang theory accepted over the steady state theory?

Answer 17

It is the only theory that explains the cosmic microwave background radiation

Question 18

What is cosmic microwave background radiation?

Answer 18

Low frequency electromagnetic radiation coming from all parts of the universe

Question 19

How does big band theory explain the cosmic microwave background radiation?

Answer 19

Just after the big bang the universe was very hot so everything in the universe emitted high frequency radiation

As the universe expanded it cooled so the radiation dropped in frequency to microwaves

Question 20

What are the 2 problems with the big bang theory?

Answer 20

There are observations the theory can’t explain (universe’s expansion is increasing when it should be slowing)

No explanation for what caused the explosion