P3.4 Motion of particles

Question 1

What is particle physics?

Answer 1

The study of subatomic and fundamental constituents of matter

Question 2

What are sub-atomic particles?

Answer 2

Particles smaller than atoms

Question 3

What are fundamental particles?

Answer 3

Particles that cannot be broken down into smaller units

Question 4

What particles are thought to be fundamental?

Answer 4

Quarks, anti-quarks, electrons and positrons

Question 5

How do scientists test new theories and models in particle physics?

Answer 5

They repeat experiments and critically evaluate the work published in science journals

Question 6

What is the LHC?

Answer 6

A particle accelerator

Question 7

Why is a particle accelerator used?

Answer 7

To collide particles at high energies to break them down into smaller ones

Question 8

What does circular motion require to keep moving in a circle?

Answer 8

A centripetal force

Question 9

What is a resultant force?

Answer 9

The total force from two or more forces acting on a single object

Question 10

How do you find the resultant force?

Answer 10

By adding the forces together while taking into account their direction

Question 11

What is a centripetal force?

Answer 11

A resultant force acting inwards along the radius

Question 12

What happens when an object travelling in a circular motion loses its centripetal force?

Answer 12

It travels in a straight line at a tangent to the circular path it was following

Question 13

What provides a centripetal force?

Answer 13

Tension

Question 14

Why is an object moving in circular motion accelerating even though the speed doesn’t change?

Answer 14

Because it is constantly changing direction

Question 15

What are cyclotrons?

Answer 15

Particle generators which bend moving charged particles into circular or spiral paths

Question 16

What produces the centripetal force required in a cyclotron?

Answer 16

A constant magnetic field applied at right angles to the particles motion

Question 17

What are the magnetic field regions in a cyclotron shaped as?

Answer 17

D-shaped

Question 18

What does the voltage in a cyclotron do?

Answer 18

Accelerate the charged particles

Question 19

Where is the voltage placed in a cyclotron?

Answer 19

Across a gap between the two D-shaped magnetic field regions

Question 20

What happens to the path of particles in a cyclotron as their speed increases?

Answer 20

It spirals outwards

Question 21

What happens once particles leave a cyclotron?

Answer 21

They travel in a straight line towards a specific target

Question 22

What happens when a high-energy proton collides with a stable element?

Answer 22

The nucleus can change into an unstable nucleus of a different element

Question 23

What is a radioactive isotope?

Answer 23

An unstable isotope that emits radiation

Question 24

What produces the short-lived isotopes used in PET scanners?

Answer 24

Small cyclotrons

Question 25

What type of collision does a ball dropped on the ground undergo?

Answer 25

Inelastic collision

Question 26

What is inelastic collision?

Answer 26

A collision where kinetic energy is not conserved

Question 27

What can kinetic energy in an inelastic collision be transferred as?

Answer 27

Heat or sound energy

Question 28

What is kinetic energy?

Answer 28

Movement energy

Question 29

Why does a ball not rebound to the same height after it's been dropped?

Answer 29

Because kinetic energy has been transferred so it's not the same as before

Question 30

What does LHC stand for?

Answer 30

Large Hadron Collider

Question 31

What is the formula for calculating momentum?

Answer 31

``` p = mv Momentum = mass x velocity ```

Question 32

What is momentum?

Answer 32

A measure of the strength of movement

Question 33

What happens to momentum in all collisions?

Answer 33

It is conserved

Question 34

What happens to kinetic energy in an elastic collision?

Answer 34

It is conserved

Question 35

What is a vector?

Answer 35

Something that has both a size and a direction

Question 36

What type of value for momentum will an object moving backwards or to the left have?

Answer 36

Negative

Question 37

What is momentum measured in?

Answer 37

Kg m/s

Question 38

What is anti-matter?

Answer 38

Matter that has particles of the same mass and properties as their counterparts but opposite electrical charges

Question 39

What is the anti-matter of an electron?

Answer 39

A positron

Question 40

What happens when an electron and positron collide?

Answer 40

Total annihilation of the particles and the production of two gamma rays that move in opposite directions

Question 41

What do the basic conservation laws of physics apply to?

Answer 41

Mass, momentum and energy

Question 42

What is mass-energy equivalence?

Answer 42

The idea that destroyed mass can be converted into an equivalent amount of energy in order to obey conservation laws

Question 43

Who came up with the idea of mass-energy equivalence?

Answer 43

Einstein

Question 44

What is the formula for calculating the energy of a system from something that uses mass-energy equivalence?

Answer 44

E = mc^2 | Energy of a system = mass x the speed of light squared

Question 45

What is the speed of light?

Answer 45

3 x 10^8 ms^-1

Question 46

What is the mass of an electron?

Answer 46

9 x 10^-31 kg

Question 47

What is the energy equivalent of the mass of an electron?

Answer 47

8 x 10^-14 J

Question 48

What is the total amount of energy released from a positron-electron annihilation?

Answer 48

1.6 x 10^-13

Question 49

What does PET scanner stand for?

Answer 49

Positron emission tomography scanner

Question 50

What does the radioactive tracer a person about to receive a PET scan emit?

Answer 50

Positrons

Question 51

How are gamma rays produced in a PET scanner?

Answer 51

From the collision of positrons from the tracer and electrons from the scanner

Question 52

How does a PET scanner locate where a tracer has come from?

Answer 52

Through triangulation; it detects the two gamma rays emitted in opposite directions and can calculate where it came from