How many star are thier in the universe

There is an average of 100 billion stars per galaxy. But you are looking for a universe, which is bigger than a galaxy.

According to UCSB Science Line, there are about 1 trillion billion stars in the observable universe. That's one 1 and twenty-one 0's.

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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no

sodium is solid at rt