Physics
posted by John .
Im having trouble understanding the concept of pressure. Help please!
What is the pressure at the bottom of a tube of mercury that is 0.2 m deep?
An elephant with a mass of 1000 kg stands on a circus platform that weighs 50 kg. The area of the bottom of the platform is 1.25 m². How much pressure is exerted on the floor beneath the platform?
Two barometers are identical except that one is filled with water while the other is filled with benzene. In which barometer will the liquid rise higher, and by how much?
If you increase the pressure on the air inside a cylinder to three times its original value, the volume of the air inside the cylinder will be ____________________.

Use the formulas
pressure = (force)/(area)
and
(pressure) = (density)*(height)*g + Po
where Po is atmospheric pressure at the top of the column (for an open manometer)
We will gladly critique your thinking if you will make an effort. 
for the elephant one you use the formula
F/A = mg/A
m= mass of elephant + mass of platform
g= 10
a= area of the platform
hope this helps!