A 65 kg bungee jumper leaps from a bridge. She is tied to a bungee cord that is 11m long when unstretched, and falls a total of 30m .

Question

A 65 kg  bungee jumper leaps from a bridge. She is tied to a bungee cord that is 11m  long when unstretched, and falls a total of 30m .

Part a) Calculate the spring constant of the bungee cord assuming Hooke's law applies.

part b)Calculate the maximum acceleration she experiences.

drwls · Accepted Answer

When fully stretched X = 19 m beyond the unstretched length, the stored potential energy (k/2)*19^2 in the cord equals the gravitational potential energy loss, (M*g*30 m). Therefore,

k/2 = M*g*30/(19)^2 = 52.9
k = 105.8 N/m

emmie · Answer

i got that answer but for part b i got 9.8 is that right ?

drwls · Answer

No, there is a larger negative acceleration at maximum stretch. I am sorry I overlooked the second part of your question. Look for my answer in a later post.