Consider the acceleration of an object that is undergoing simple harmonic motion. is this acceleration zero or nonzero?

Non-zero

Explanation:

For a simple harmonic motion, the restoring force is given by

F = -kx (1)

where

k is the spring constant

x is the displacement of the system with respect to the equilibrium position

According to Newton's second law, the acceleration of the system is given by

a = F/m (2)

where

m is the mass of the system

So if we substitute (1) into (2) we find

a = -kx/m

so the acceleration is directly proportional to the displacement. Since the value of the displacement  in a simple harmonic motion constantly changes, the acceleration changes as well, so it is non-zero (apart from the instant where the displacement is zero, x = 0, when the acceleration is also zero)

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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massxgravity x heght=weightxheight= pe

4900=490xh

h=10