Our Dynamic Universe

Question 1

What is acceleration?

Answer 1

Acceleration is the change in velocity per second

Question 2

What is Gravitational Field Strength?

Answer 2

This is defined as the weight per unit mass

Question 3

Satellite Orbits

Answer 3

Satellite experiences unbalanced force, must be accelerating due to change in direction, constant horizontal velocity and constant vertical acceleration causes curved path. Curve in satellite is same as earth so stays at the same height above the surface, orbit.

Question 4

Lift experiment: what does it mean when there is a larger upward force?

Answer 4

There is an upward acceleration

Question 5

Lift experiment: what does it mean when forces are balanced?

Answer 5

The lift is at rest or has a constant velocity

Question 6

Lift experiment: what does it mean when there is a larger weight?

Answer 6

There is a downward acceleration

Question 7

What is conservation of energy?

Answer 7

The principle that total energy is conserved

Question 8

What is momentum

Answer 8

Momentum is the product of the mass and velocity of an object

Question 9

What happens to kinetic energy in an elastic collision?

Answer 9

It is conserved

Question 10

What happens to total momentum in a elastic collision?

Answer 10

It is conserved

Question 11

What happens to kinetic energy in an inelastic collision?

Answer 11

It is lost

Question 12

What happens to total momentum in an inelastic collision?

Answer 12

It is conserved

Question 13

What happens to momentum in an explosion?

Answer 13

It is conserved

Question 14

What happens to kinetic energy in an explosion?

Answer 14

It is greater after

Question 15

What happens to total energy in an explosion?

Answer 15

It is conserved

Question 16

What is impulse?

Answer 16

The change in momentum of one mass in a collision or explosion

Question 17

What are the postulates?

Answer 17

All observers measure the same speed of light and laws of physics are the same in all frames

Question 18

What is time dilation?

Answer 18

Time dilation is when the time on a moving clock appears to have slowed when measured by a stationary observer

Question 19

What is length contraction?

Answer 19

Length contraction is when an object appears to be smaller when measured by a stationary observer when it is moving relative to them

Question 20

Why can the observer ignore relativistic effects with an object with a velocity less than c?

Answer 20

Because (v/c)^2 is approximately equal to zero when v is less than or equal to c

Question 21

What is the Doppler effect?

Answer 21

The name given to the frequency shift heard by an observer to a sound with relativistic motion between them

Question 22

What happens to the frequency when a source is moving away from a stationary observer?

Answer 22

It will be lower

Question 23

What happens to the frequency when a source is moving towards a stationary observer?

Answer 23

It will be higher

Question 24

What was the Big Bang?

Answer 24

The Big Bang was an inflation of a singularity

Question 25

What is evidence for the Big Bang?

Answer 25

Red shift of galaxies, cosmic microwave background radiation and the abundance of light elements

Question 26

What is red shift?

Answer 26

Red shift indicates that the source of light is moving away from the observer

Question 27

What is Cosmic Microwave Background Radiation?

Answer 27

It proves the Big Bang because when plotted against wavelength it produces a graph that shows the universe is cooling after the Big Bang

Question 28

Abundance of light elements

Answer 28

After the Big Bang there were only fundamental particles from these small lighter elements are likely to form which is constant with observations

Question 29

What is dark energy?

Answer 29

This is the name given to the energy source that cosmologists think is causing this expansion

Question 30

What is dark matter?

Answer 30

It is not normal matter as it produces a gravitational effect but does not interact with normal matter