Spring mechanics question easy

  • Thread starter ronaldor9
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Homework Statement



A block of mass m1 = 8 kg hangs from the ceiling on an ideal, massless spring with spring constant k = 65 N/m. With the block hanging on the spring, the total length of the spring is L = 3.5 m. When a second block with an identical mass of m2 = 8 kg is tied to the first with a massless string, the spring stretches an additional h0 = 1.5 m.

The string is cut so that mass m2 falls away. What is the maximum velocity of mass m1?




The Attempt at a Solution


[tex] \frac{kx^2}{2}=\frac{mv^2}{2} [/tex]
x=1.5 and solving for v gives 4.3
but the answer is 3.42?
 

Answers and Replies

  • #2
tiny-tim
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Hi ronaldor9! :smile:
… With the block hanging on the spring, the total length of the spring is L = 3.5 m. When a second block with an identical mass of m2 = 8 kg is tied to the first with a massless string, the spring stretches an additional h0 = 1.5 m.

x=1.5 and solving for v gives 4.3
but the answer is 3.42?
1.5 isn't x …

you have to (find and) add on the bit of x that's already in the 3.5. :wink:
 

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