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tgoodspe

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**Energy in a Spring-Mass System - Help! :)**

**1.A horizontal spring-mass system has low friction, spring stiffness 235 N/m, and mass 0.3 kg. The system is released with an initial compression of the spring of 7 cm and an initial speed of the mass of 3 m/s.**

**(a). What is the maximum stretch during the motion?**

## The Attempt at a Solution

So I tried using the Energy Principle to find the maximum stretch;

Kf + Uf = Ki + Ui + W

Kf = 0

W= 0 (I think right because there's no outside force?)

SO: 0 + (.5)(ks)(s^2)final = (.5)mv^2 + (.5)(ks)(s^2)initial

By plugging in variables I got that;

(.5)(ks)(s^2)final = 5758.85 J

(s)final = SQRT(2(5758.85)/(235N)) = 7m

(s)final = 7m

This isn't the right answer, which also sort of makes sense because the stretch shouldn't be the same as the compression. Which makes me think that my initial equation is flip flopped or something of the sorts.