Calculating Weight of Truck on Ferry Boat

[Lunar Guy]

[SOLVED] buoyant 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 buoyant force = weight of the fluid displaced)

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

m = ρV
(mass = density × volume)



3. Well, the volume 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?

 

[mgb_phys]

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.

 

[Lunar Guy]

All right! Thanks. :)

Problem solved!

EDIT: Ermmm... How do I mark it solved?

 

[Lunar Guy]

Found it. :)