What can we say about the rock as it falls to earth? a) it accelerates as it falls. b) it falls at a constant rate of speed. c) it is at a constant velocity as it falls. d) it accelerates until it reaches a peak velocity, then decelerates.

A)It accelerates as it falls.

Unless it is has no acceleration or deceleration then it will speed up because as its mass will weigh the rock down making it go faster.

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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the area between the graph and the t axis