How to Calculate Buoyant Force and Volume of a Submerged Object?

[missnola2a]

doppler effect quick question!

Homework Statement

An ambulance traveling at speed 31 m/s is producing a loud sound of frequency 895 Hz. You see the ambulance in your rear view mirror as the ambulance approaches you and you slow down to 14 m/s as a law obeying citizen (hehehe we know now).

Homework Equations

fo=fs((v +- Vo)/(v+-Vs))

should it be:

895 (330-14)/(330-31)?

The Attempt at a Solution

 

[rl.bhat]

You are wright.

 

[missnola2a]

hi, thanks so much! i got that one... will you look at this one? I feel like I am so close.

https://www.physicsforums.com/showthread.php?p=2286412#post2286412

OR

A chunk of carbon steel with density, ρ = 7.84 g/cm3 , is completely submerged in fresh water. The chuck of steel weighs 39 N more in air than in water. Please answer the following:
(a) Find the buoyant force acting on the chuck of steel.
N
(b) Find the the volume of the chuck of steel.
m3
(c) What is the mass of the chuck of steel?

2. Homework Equations


Fw(air)=Fw(water) + 39 N

d=m/v

Fb=gp(f)V

BUT I don't know how to find the volume.

density of air is 1.16 kg/m3
density of water is 1.0x10^3


3. The Attempt at a Solution

once I get the VOLUME I can find the relative weights by using rho*g*v
and Fw(water)+ 39N = Fw(air)