[ghostanime2001]

1. The problem statement, all variables and given/known data
Atmospheric pressure is 100 kPa and a depth of 1m in water is equivalent in pressure to 10 kPa. A jam tin, open end down, is forced under water until the water half fills the can. At this stage, how far beneath the surface is the can? (ans is 10 m)


2. Relevant equations
I DONT'T UNDERSTAND WHY 10 metres! T_T


3. The attempt at a solution
So from what I know, I must use Boyle's Law.
P1 = 100 kpa
P2 = ?
V1= ?
V2 = 1/2 V1

P1V1=P2V2
100V1=P2(1/2 V1)
100V1=1/2 P2V1 <---Don't the V1's cancel out?
200=P2

using ratio's:
1m/10 kPa = x/200 kPa
x=20 m

Why is my answer different from my worksheet (10m) ??

Any help is greatly appreciated!
Thanks

[Borek]

200=P2

Correct.

Where does this pressure comes from?

[ghostanime2001]

water PLUS atmospheric pressure ?

[ghostanime2001]

What?

[Borek]

water PLUS atmospheric pressure ?

Yes. How much of those 200 kPa is water?

[ghostanime2001]

100 Kpa? 100 Kpa from atmosphere already