P2.7 Energy from the nucleus

Question 1

What is nuclear fission?

Answer 1

the splitting up of a nucleus into two (approximately equal) fragments and the release of two or three neutrons

Question 2

What is a chain reaction? How can it be controlled?

Answer 2

a chain reaction occurs in a nuclear reactor when each fission events causes further fission events

Question 3

What is nuclear fusion?

Answer 3

the process of forcing two nuclei close enough so they form one larger nucleus

Question 4

How does a nuclear fusion reactor work?

Answer 4

a fusion reactor needs to be a high temperature before fusion takes place
energy is released when the two nuclei collide

Question 5

Where is the moat important place that fusion takes place?

Answer 5

The sun - nuclear fusion in the sun’s core releases energy

Question 6

What are some of the issues linked wit nuclear energy?

Answer 6

nuclear waste - has to be carefully stored in safe and secure conditions for many years
the risk to workers or locals - cancer and radiation poisoning
disasters like Chernobyl

Question 7

What was the early universe like?

Answer 7

before galaxies and stars formed the universe was a dark patchy cloud of hydrogen and helium
the force of gravity pulled matter into galaxies and stars

Question 8

Explain the life cycle of a star

Answer 8

protostar- gas and dust cloud

low mass:
protostar–>main sequence star–>red giant–>white dwarf–>black dwarf

high mass:
protostar–>main sequence star–>red supergiant–>supernova–>neutron star–>black hole (if sufficient mass)

Question 9

How are chemical elements formed?

Answer 9

elements up to iron are formed inside stars as a result of nuclear fusion
elements heavier than iron are formed in supernovas