1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Hooke's law and buoyancy

  1. Mar 6, 2016 #1
    1. The problem statement, all variables and given/known data
    A ball with a mass of 250 g and a volume of 126 cm^3 is hung vertically to a spring the springs length becomes 0.690 m.Then the ball is slowly submerged in water with a density of 1000 kg /m^3 then the spring's length becomes 0.620 m.

    Find Buoyancy force of the water on the ball

    What was the spring's original length

    What is the constant (k) of the spring

    2. Relevant equations

    Fb=density x volume x gravity
    3. The attempt at a solution
    I attempted to solve it by creating a the following system of equations
    0.250 x 9.81 = K(0.690-Li) and 0.250 x 9.81 - 1000 x 126^-6 x 9.81 = K(0.620-Li)
    Every time I solve it I get that K=17.65 and Li= 0.551 m
    The answer sheet says that K=20.6 and Li = 0.561
    Please help I suspect that my mistake is in the second equation but am not too sure
  2. jcsd
  3. Mar 6, 2016 #2
    I obtain your equations and your answers.
  4. Mar 6, 2016 #3
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted