Work done by a variable force

  • #1
8
0
A 1.2 kg block is held against a spring of force constant 1.0 x 10^4 N/m, compressing it a distance of 0.15m. How fast is the block moving after it is released and the spring pushes it away?
 

Answers and Replies

  • #2
406
15
think about conservation of energy, and the potential energy stored in the spring before release
 
  • #3
8
0
i know that k=1.0 x 10^4
x(final)=-0.15
x(initial)=0
work=1/2kx^2= -112.5

but i dont know how to find the velocity

i tried using v^2=k/m (x^2)
and recieved 13.69m/s
 
  • #4
406
15
Do you think that's wrong?
You solved for v. v is the velocity. well technically the speed here, but I'd assume that's what your teacher meant.
 
  • #5
311
23
Looks good, average force seems to satisfy.
 

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