Our Dynamic Universe

Question 1

List of scalar and vector quantities

Answer 1

Scalars:
Speed, Distance, Mass, Time, Temperature

Vectors:
Velocity, Displacement, Acceleration, Force, Momentum

Question 2

Steps to answering a projectiles question

Answer 2

1. Calculate Uv and Uh using v cos theta = Uh and v sin theta = Uv
2. Find maximum height using v² = u² + 2as
3. Find how long it took to travel the full distance using v = u + at, then multiply the time by 2
4. Find out how far it went horizontally using s = vt

Question 3

Forces in a lift

Answer 3

Heavier - accelerating upwards, decelerating downwards

Lighter - Accelerating downwards, decelerating upwards

Question 4

Forces down a slope

Answer 4

down the slope - mg sin theta
directly down - mg
force going into the slope - mg cos theta
friction = force down the slope if object is moving at a constant speed

Question 5

What is terminal velocity

Answer 5

It’s when the air resistance equals the weight of a free falling object, the forces are balanced and the object is now falling at a constant velocity.

Question 6

Collisions between masses

Answer 6

Inelastic - momentum is conserved, total energy is conserved, but kinetic energy is less (decreases)

Elastic - All three factors are conserved

Explosion -momentum is conserved, total energy is conserved, but kinetic energy is more (increases)

Question 7

Momentum equations

Answer 7

P = mv
m1 u1 + m2 u2 = m1 v1 + m2 v2

Law of conservation of momentum meaning momentum before = momentum after but only if no external forces are applied.

Question 8

Impulse equation

Answer 8

Ft = mv - mu

P = the area under the Ft graph

Question 9

What is time dilation

Answer 9

If someone is travelling at a speed close to the speed of light in a vacuum, they will experience less time than someone stationary on earth as they are in there own frame of reference. T dash is larger

Question 10

What is length contraction

Answer 10

A person on a space craft travelling at a speed close to the speed of light will measure the spacecraft to be the actual length of it whereas someone measuring it from earth will measure a smaller value. L dash is smaller

Question 11

What is the Doppler effect?

Answer 11

When the frequency of a moving source changes for observers. When the source is moving away, the frequency is lower (wavelength increases +) and when it is moving towards you, it is higher (wavelength decreases -)

Question 12

What is redshift

Answer 12

Redshift = frequency decreasing, wavelength increase so source is moving away
Blueshift = frequency increasing, wavelength decreases so source is moving closer

Question 13

What is hubbles law

Answer 13

It is the evidence that the universe is expanding from a single point, as the further a galaxy move away, the faster they go

Question 14

Age of the universe?

Answer 14

1 divided by hubbles constant

Question 15

Stellar objects

Answer 15

hotter objects have a smaller peak wavelength

hotter objects emit more radiation per unit surface area

Question 16

What is CMBR

Answer 16

CMBR is the cosmic microwave background radiation which is more evidence for the big bang theory. It is the radiation from the young universe which has stretched as the universe has expanded

Question 17

What is olbers paradox

Answer 17

It is not day time all the time because the light from distant stars are dimmed cause they are red shifting from the observer and are too distant to create enough light to make it day

Question 18

What is dark matter

Answer 18

It is a mass that is said to make up the rest of the universe as galaxies and stars were measured to be a certain mass but the actual mass was larger and was unknown why, so dark matter was the solution.

Question 19

what is dark energy

Answer 19

It is the evidence for the increasing rate of the expansion of the universe as it is said to be the thing accelerating galaxies away from each other. Cannot be observed but can be measured and is siad to make up 74% of the universe.