Hidden object at bottom of pool with a raft.

[pdeco1]

Homework Statement

A thief hides a diamond in the center of the bottom of a cylindrical pool of water of depth 3m and diameter 10m by placing a circular raft on the surface of the water. The center of the raft is directly above the diamond. What is the minimum radius of the raft that will completely hide the diamond?

Homework Equations

Critical angle formula.
SOHCAHTOA

The Attempt at a Solution

I found the critical angle Theta(c) = sin^-1(n2/n1) = 1/1.33 = 48.7 degrees.


The depth of the pool is 3m. tan48.7 = O/A = 3(tan48.7) = 3.41, which is the radius of the raft.

Thanks.

 

[pdeco1]

Bump - Am I doing this problem correctly?

 

[gneill]

I get a raft radius of 3.42m. It looks like your method is good, but you may want to be careful about carrying enough significant figures through the calculations right to the end (where the result is rounded).