I have a question (I understood 41 but I don't understand the others) about the following problem. I have attached the question, the given answer, and the work I did. Thank you so much!

i believe it is b. what was the cause of the big bang

hope this !

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

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f=ma newton's second law 7x8=56n

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.