What is the speed of the chain at this instant?

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The discussion revolves around a physics problem involving a chain of metal links being pulled with a force on a low-friction table. The user calculated the speed of the chain to be 8.4439 m/s and determined the change in energy to be 248.4 joules. However, they encountered an error while attempting to calculate the thermal energy, mistakenly dividing instead of subtracting kinetic energy from the total energy. Another user pointed out this mistake, emphasizing the importance of basic math in solving the problem. The thread highlights the collaborative nature of problem-solving in physics forums.
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Homework Statement




A chain of metal links with total mass M = 6 kg is coiled up in a tight ball on a low-friction table. You pull on a link at one end of the chain with a constant force F = 69 N. Eventually the chain straightens out to its full length L = 1.0 m, and you keep pulling until you have pulled your end of the chain a total distance d = 3.6 m.

before this question i have already answered these questions. might need the info to solve not sure though.

(a) Consider the point particle system:
What is the speed of the chain at this instant?
8.4439 m/s


Consider the real system:
What is the change in energy of the chain?
delta(E) = 248.4 joules


The Attempt at a Solution


i solved conservation of energy like
Ef = Ei + W + Q
then
Ef = 248.4 + Q where Q = 0
then
final Ke + Ethermal = 248.4
solved for Ethermal = 248.4 / Ke or 248.4/(1/2mv^2) using v found above
i get 1.1613 J but that is wrong. where did i mess up??
 
Last edited:
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solved for Ethermal = 248.4 / Ke or 248.4/(1/2mv^2) using v found above
i get 1.1613 J but that is wrong. where did i mess up??

Instead of dividing by Ke...You have to subtract by Ke.
 
haha i need to go back to basic math.
thanks sriceb01
and welcome to the forums.
this site is great!
 

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