Question

1. In a star of at least this many solar masses, helium burning begins before electron-degeneracy pressure sets in, avoiding the helium flash:

A. 0.08

B. 0.25     

C. 2.5

D. 8

E. 12

2. A dying star must have this many solar masses to leave behind a neutron star:

A. <0.25

B. 0.25 - 8     

C. 8 - 30

D. >30

3. A 100-meter long train passes you, going 99% the speed of light. How long do you measure it to be, in meters?

A. 2.0

B. 14     

C. 710

D. 1000

Answer 1

1. In a star of of around 2.25 Mo helium starts to burn without it's core becoming degenerate or in other words, before the electron degeneracy pressure comes into the picture. So, option C is the correct alternative. (2.5)

2. The minimum mass required for the formation of a neutron star is given by the Chandrashekhar Limit, and it is around 1.4 solar masses. So, the range of 0.25-8 solar masses is correct. Option B is the correct alternative.

3. Going by the principle of relativity , the theory of length contraction can be applied in this case.

L = L(0) sqrt(1-v^2/c^2)

L= 100*sqrt(1-0.99c^2/c^2)

L= 100*sqrt(1-0.99)

L= 100*0.1 = 10 metres (Answer)