It's kinda weird. I can't figure out how they got the answer to number 80, I tried alotta different weird things, nothing worked. But when I calculated escape velo of the B0 star, it is greater then the original speed, making me think the answer should be never? They probably did something along the line of accelerating the gas (by a factor of 278) due to the gravitational acceleration of the neutron star, I don't know what.OrigamiPlanet wrote:This problem set from this particular PA finals is really confusing me, problems 80-83. Could someone help me understand what formula or formulas I need to be using for this?

Test link:

https://scioly.org/wiki/images/7/73/Pen ... stions.pdf

Key link:

https://scioly.org/wiki/images/1/12/Ans ... states.pdf

Thanks!

81 assuming you have the answer to 80, set 2.48E16=1/2mv^2, solve for v, and divide by c to get 74%

82, also assuming you have the answer to 80, find rest energy with e=mc^2 and divide 2.48E16 by 9E16 to get 28%

83 I did that your given the energy is 8.5E29 and find mass with e=mc^2 and divide 8.5E29/9E16 to get 9.4E12, but this disagrees with the key that says 3.4E13.

Either the key on this test is wrong on some parts, or I'm being very stupid right now.