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!

Bouyant force

  1. Feb 10, 2008 #1
    [SOLVED] Bouyant force

    1. A ferry boat is 4.0 m wide and 6.0 m long. When a truck pulls onto it, the boat sinks 4.00 cm (0.04 m) in the water. What is the weight of the truck?

    2. F(sub: B) = F(sub: g)[displaced fluid] = m(sub: f)g
    (magnitude of bouyant force = weight of the fluid displaced)

    F(sub: B) = F(sub: g)[object] = m(sub: o)g
    bouyant force = weight of floating object

    m = ρV
    (mass = density × volume)

    3. Well, the voulme of the boat is (4.0 m)(6.0 m)(0.04 m) = (0.96 m³); I mean, the volume of the displaced water is that. ;)

    Density of fresh water = 1.00 × 10³ kg/m³

    F = ρV(g)
    F = (1.00 × 10³ kg/m³)(0.96 m³)(9.81 m/s²)
    F = 9.4 × 10³ N

    Am I correct?
    Last edited: Feb 10, 2008
  2. jcsd
  3. Feb 10, 2008 #2


    User Avatar
    Science Advisor
    Homework Helper

    Correct - and an extra bonus point for quoting the weight of the truck not it's mass.
    Although you will probably get the answer marked wrong by some dumb online marking system that expects mass.
  4. Feb 10, 2008 #3
    All right! Thanks. :)

    Problem solved!!!

    EDIT: Ermmm... How do I mark it solved?
  5. Feb 10, 2008 #4
    Found it. :)
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook