posted by anonymous .
An 85kg person bounces on a bathroom scale having a force constant of 1.50*10^6 N/m. The amplitude of the bounce is 0.200 cm. What is the maximum energy stored in the spring?
I use the formula mg = kx, solved for x, and got 5.55333 * 10^-4.
Then I added the amplitude, .002 m, to get 2.5553*10^-3, which was wrong. I also tried the answer without adding the amplitude, and that was wrong.
Where could I be going wrong? There was some discussion on the forum of my online class saying that the question might have some issues...where is the error here?
ω = sqrt(k/m) = sqrt(1.5e6/85) = 133rad/s
x(t) = 0.002sinωt = (1/500)*sinωt
v(t) = (ω/500)*cosωt
vmax = (ω/500) = 133/500=0.266 m/s
max energy= 1/2 m vmax^2
you know m, and vmax.
check my math.