p16

Question 1

life cycle of a star - nebulla

Answer 1

large cloud of dust and gas being pulled together/inwards due to gravity.

Question 2

life cycle of star - protostar

Answer 2

as it is pulled inwards due to gravity, conditions of temperature and pressure become favourable to start fusion of hydrogen gas to form helium.

Question 3

life ycle of star - main sequence stage

Answer 3

when inward force due to gravity = outward force due to fusion

Question 4

life cycle of star - red giant/red supergiant stage

Answer 4

when the star runs out of hydrogen, the fusion stops (the core compresses and heats up because inward force of gravity is greater than outward force due to pressure of expanding gases).
under these conitions, helium undergoes fusion to form elements up to iron

Question 5

life cycle of star - white dwarf

Answer 5

happens after red giant stage (when the star is around same size as sun)
it is when fusion stops completley, and the star starts cooling down and compresses (due to gravity)

Question 6

life cycle of star - black dwarf

Answer 6

• after white dwarf stage (when star is same size as sun)
  it is when the star is completley cold.

Question 7

life cycle of star - supernova

Answer 7

• after red super giant stage (star is larger than size of sun)
  the core of star collapses causing a giant explosion.

Question 8

neutron star (black hole)

Answer 8

when the star is very big, the neutron star will continue to collapse under the force of gravity until it forms a black hole.

Question 9

what does an articifial satellite orbit?

Answer 9

any object or body in solar system

Question 10

what does a planet orbit?

Answer 10

sun

Question 11

what is nuclear fusion

Answer 11

light nuclei are joined to produce heavier nuclei, releasing energy in the process due to the conversion of a small quantity of mass into energy.

Question 12

how does an object orbit another?

Answer 12

a smaller body object wll orbit a larger body by a force pulling things towards the larger body (gravity)

Question 13

what is an orbit?

Answer 13

the curved path of one celestial object or spacecraft around another celestial object

Question 14

why is moon’s orbit said to be accelerating?

Answer 14

speed is same, but as it is changing direction, velocity is constantly changing.
acceleration = change in velocity/time

Question 15

how do u maintain a stable orbit?

Answer 15

the smaller an object’s orbit is, the faster the object travels, because there is not as much gravitational pull.

Question 16

what is the big bang theory?

Answer 16

universe began from a small region that was extremley small and dense.
mass distance and time was created.
it is constantly expanding.

Question 17

explain the red shift theory

Answer 17

• as the light of stars move towards the red end of the spectrum that means that the wavelength of the light recieved by us is increasing.
• this can happen only when the stars are moving away from us - evidence of the big bang theory (expanding universe)