# physics B

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This is the first question on the 2003 ap physics b exam. I need help with part e.
It shows a diagram of a pulley with two students. student A is on the ground with a mass of 70kg holding on to the pulley while student B is in the air with a mass of 60.

Question:
with what minimum acceleration must Student B climb up the rope to life student A off the floor?

• physics B -

Tension in the rope must equal 70 g = 70*9.8 = 686 Newtons
force on Student B = 686 tension up and mg = 60*9.8 = 588 N down weight
Net force up = (686 - 588)
= m a = 60 * a
a = (686-588)/60

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