# Nwebie,formula for drag of submerged object

1. Aug 18, 2008

### alibaba2

hi, newbie needs a little help...what is the formula and could someone please take the time to explain in detail how to compute the elements in the formula for the following task.

a submerged styrofoam rectangle with size H 100cm x L 15cm x W 50 cm. the object is submerged at 20 meters (60ft) underwater. it will be rising upward with the top side (750cm^2 area )
based on formula for drag, i need to calculate how long it will take to surface at the top, and what is its speed.

2. Aug 18, 2008

### Topher925

There really no hand calculation for this. You can define buoyancy force using Bernoulli's equation however the drag is rather difficult. It relies on the surface and geometry of the block which can change significantly depending on the depth its rising from. My suggestion is just to guesstimate with experimenting.

3. Aug 18, 2008

### alibaba2

surface of the rectangular block is styrofoam, coated with thin fibreglass film, so it is 100% smooth. shape is defined in the initial text.
10x