Physics but Shorter

Question 1

Define inertia

Answer 1

How hard it is to change the motion of an object

Question 2

State Newton’s First Law

Answer 2

A body will remain at rest, or continue to move with a constant velocity unless acted upon by an external (resultant) force

Question 3

Resultant force definition

Answer 3

The total force acting upon an object

Question 4

Newton’s Second Law

Answer 4

Resultant force = mass x acceleration (this means that acceleration is directly proportional to resultant force)

Question 5

Define weight and mass

Answer 5

Weight - the measure of how large the force of gravity is on an object (N)
Mass - the measure of how much matter an object has (kg)

Question 6

What is Newton’s Third Law

Answer 6

If object A exerts a force on object B, object B also exerts an equal and opposite force on object A.

Question 7

What kind of energy is kinetic energy

Answer 7

Movement energy - faster objects have more kinetic energy

Question 8

How is energy taken away from KE and GPE

Answer 8

It becomes friction (work done)

Question 9

State Hooke’s Law

Answer 9

The extension of a material is directly proportional to the force applied

Question 10

How is work done represented

Answer 10

As the area under a force extension graph

Question 11

What are the ways vehicles lose energy and what are the ways to improve them

Answer 11

• Aerodynamic losses: more streamlined
• Rolling resistance: correctly inflated tyres from right material
• Idling losses: stop-start systems turn off the engine in traffic
• Inertial losses: lighter car (carbon fibre, not heavy metal)

Question 12

Car safety features

Answer 12

• Seat belt
• Crumple zone
• Air bag
• Side-impact bars (strong bars inside car doors)
• Passenger cell (a rigid cage around passengers)

Question 13

What do car safety features do

Answer 13

They slow the passengers down as gradually as possible which means the force also decreases - they also increase the distance over which energy is transferred (force=work done/distance)

Question 14

Momentum fact file

Answer 14

• Momentum is the amount of motion an object has
• Measured in kgm/s
• Total momentum before interaction = total momentum after interaction

Question 15

Two words relating to kinetic energy in car crashes

Answer 15

Elastic collision and inelastic collision (inelastic means kinetic energy is lost)

Question 16

What accelaration is given by gravity

Answer 16

10m/s squared, so if an object is thrown up this becomes -10

Question 17

Moment fact file

Answer 17

• A moment is the turning effect of a force
• Moment = force x distance to the pivot
• The sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the same point
• When the moments of each side are balanced they are in equilibrium

Question 18

What is an astronomical unit

Answer 18

The mean distance from the earth to the sun

Question 19

Give the main stages of the life cycle of a star

Answer 19

• Protostar
• Main sequence
• Red giant
• White dwarf
  OR
• Red supergiant
• Supernova
• Black hole / neutron star

Question 20

What creates outwards pressure in stars

Answer 20

Gas and radiation pressure

Question 21

Two types of evidence for the big bang

Answer 21

• Cosmological red shift
• Cosmic microwave background radiation

Question 22

Key terms for cosmological red shift

Answer 22

• Continuous spectra: a full rainbow of light
• Absorption spectra: a continuous spectra that’s been blocked

Question 23

Why are the waves in CMBR microwaves

Answer 23

Because they’ve stretched from the original gamma rays

Question 24

How does a galaxy’s distance from us correlate with red shift?

Answer 24

The further away it is the greater the redshift

Question 25

Define isotope

Answer 25

Atoms of the same element which have the same number of protons but a different number of neutrons

Question 26

Define ionising

Answer 26

When radiation interacts with cells and damages DNA (cancer)

Question 27

Alpha fact file

Answer 27

- Its symbol is below - It is a helium nucleus - It can be stopped by a thin sheet of paper or a few cm of air - It's very damaging to the body

Question 28

Beta fact file

Answer 28

- Its symbol is below - It is a fast moving and high energy electron - Can be stopped by a few mm or aluminium or 1m air

Question 29

Gamma fact file

Answer 29

- Only stopped by several cm of lead or very thick concrete, so passes easily through the body

Question 30

What is the process for storing nuclear waste

Answer 30

* It's first **cooled** in large water tanks * It's turned into a type of **glass** so it can't flow * It's placed inside **steel drums** and **sealed** in concrete * It's **buried** deep underground

Question 31

Radon gas factfile

Answer 31

* It emits alpha * It goes from uranium to radium, radon and polonium * Because radon is a gas it can be breathed in * Cornwall has the highest concentration

Question 32

What is activity and what is it measured in

Answer 32

It's the measure of decays per second and measured in becquerels - also known as the count rate

Question 33

What happens in a nuclear fission power station

Answer 33

* Uranium -235 in fuel rods absorbs a slow moving neutron which makes it unstable * The uranium decays and splits into two smaller nuclei, and a large amount of energy is released * These neutrons cause more atoms to undergo fission * This is a chain reaction

Question 34

Name features used in the reactor to stop out of control chain reactions

Answer 34

* The moderator slows down neutrons (this is either water or graphite rods) * Boron control rods are dropped into the reactor to slow the reaction - they absorb extra neutrons * The reactor is surrounded by concrete * Water acts as a coolant

Question 35

What would nuclear fusion involve and where would we get the fuel

Answer 35

Two isotopes of hydrogen making helium, taken from sea water

Question 36

Which laboratory is most advanced for fusion and what does it involve

Answer 36

The JET laboratory which has a doughnut shaped reactor where the particles are accelerated into each other