11.3 Pressure  (Page 2/3)

A cylindrical drum of radius 0.5 m is used to hold 400 liters of petroleum ether (density = .68 g/mL or 680 kg/m ³ ).

(Note: 1 liter = 0.001 m ³ )

1. Determine the amount of pressure applied to the walls of the drum if the petroleum ether fills the drum to its top.
2. Determine the amount of pressure applied to the floor of the drum if the petroleum ether fills the drum to its top.
3. If the drum were redesigned to hold 800 liters of petroleum ether:
   1. How would the pressure on the walls change?

      Would it increase, decrease, or stay the same?

   2. How would the pressure on the floor change?

      Would it increase, decrease, or stay the same?

How is pressure related to the sharpness of a knife and its ability to cut?

Why does a dull hypodermic needle hurt more than a sharp one?

The outward force on one end of an air tank was calculated in [link] . How is this force balanced? (The tank does not accelerate, so the force must be balanced.)

Why is force exerted by static fluids always perpendicular to a surface?

In a remote location near the North Pole, an iceberg floats in a lake. Next to the lake (assume it is not frozen) sits a comparably sized glacier sitting on land. If both chunks of ice should melt due to rising global temperatures (and the melted ice all goes into the lake), which ice chunk would give the greatest increase in the level of the lake water, if any?

How do jogging on soft ground and wearing padded shoes reduce the pressures to which the feet and legs are subjected?

Toe dancing (as in ballet) is much harder on toes than normal dancing or walking. Explain in terms of pressure.

How do you convert pressure units like millimeters of mercury, centimeters of water, and inches of mercury into units like newtons per meter squared without resorting to a table of pressure conversion factors?

As a woman walks, her entire weight is momentarily placed on one heel of her high-heeled shoes. Calculate the pressure exerted on the floor by the heel if it has an area of $1\text{.}\text{50}{\text{cm}}^2$ and the woman's mass is 55.0 kg. Express the pressure in Pa. (In the early days of commercial flight, women were not allowed to wear high-heeled shoes because aircraft floors were too thin to withstand such large pressures.)

The pressure exerted by a phonograph needle on a record is surprisingly large. If the equivalent of 1.00 g is supported by a needle, the tip of which is a circle 0.200 mm in radius, what pressure is exerted on the record in ${\text{N/m}}^2$ ?

Nail tips exert tremendous pressures when they are hit by hammers because they exert a large force over a small area. What force must be exerted on a nail with a circular tip of 1.00 mm diameter to create a pressure of $3\text{.}\text{00}\times {\text{10}}^9{\text{N/m}}^2\mathrm{?}$ (This high pressure is possible because the hammer striking the nail is brought to rest in such a short distance.)