Pressure - breathing through a reed

[skyhigh302]

I'm getting stumped by these questions..can someone please help me?

Homework Statement

1. In a movie, Tarzan evades his captors by hiding underwater for many minutes while breathing through a long, thin reed. Assuming the maximum pressure difference his lungs can manage and still breathe is 80.7 mmHg, calculate the deepest in cm that he could have been.

2. The gauge pressure in each of the four tires of an automobile is 240 kPa. What is the actual pressure in each tire in psi?

Homework Equations

1. 760mmHg=33 ft. of water

2. none

The Attempt at a Solution

1. I multiplied 80.7 by 33 and divided it by 760...than after that I converted it but I still get it wrong.

2. I converted the kpa to psi... Isn't that all I need to do? I converted it but I got it wrong..

 

[Doc Al]

1. I multiplied 80.7 by 33 and divided it by 760...than after that I converted it but I still get it wrong.

That seems right to me. Show your calculation.

2. I converted the kpa to psi... Isn't that all I need to do? I converted it but I got it wrong..

You need to know the meaning of "gauge pressure". Read this: http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/idegas.html#c5"

 

[skyhigh302]

1.

(80.7*33)/760=3.504ft.

=106.8019cm.

that is the wrong answer...