1. You want to describe the harmonic motion of a swing. You find out that it takes 2 seconds for the swing to complete one cycle. The swing passes through 48 degrees as it goes from high point-to-high point in its motion (passing through a center). What is the period of the swing?
What is the frequency of the swing in hertz?
What is the amplitude of the swing?
If you let the swing’s motion continue on its own, what would happen to its amplitude? Why?

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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double the distance = divide strength by 4

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form