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1. A 2.50 kg mass is hung at rest on the end of a spring held vertically from a rod. The initial
displacement of the mass is 0.065 m and the spring has a spring constant of 3 N/m. When the
spring-mass system is oscillating, the period of oscillation is -
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a. 0.91 s
b. 1.10 s
c. 5.23 s
d. 5.74 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.

read more on -

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i just did this and got a 100.

there are no contact forces mentioned on the list of choices that you've provided.

answerscientific theory;