Spring Constants - Stuck on Chad Quiz Question

[Gauss44]

---

Members don't see this ad.

The 100g mass attached to the end of a horizontally mounted spring with a spring constant of 160 N/m undergoing shm has a velocity of 4m/s as it passes through the equilibrium position of the spring. What is the amplitude of the oscillation?

Ans: .1m

I want to say 1/2mv^2=1/2kx^2, 800=1/2kx^2, 1600/160=x^2... (I suspect I keep overlooking something obvious, but have been stuck on this for a long time now.)

 

[Endure]

The mass is in g, not kg. That's your problem.

1/2mv² = 1/2kx², since the potential energy in the spring is completely converted to kinetic energy at the equilibrium position. So:

mv² = kx². Plug in the values and you get the correct answer, x (amplitude) = 0.1 m.

 

[Gauss44]

thank you