Problem Solving:
1. A typical high school student weighs 800 N and wears shoes that touch the ground over an area of 500 cm2. (6 pts)
(a) What is the average pressure his shoes exert in the ground?
(b) How does the answer change when he stands on only one foot?
2. The atmospheric pressure at sea level is about 1.0 x 105 Pa. What is the force exerted on the top of a typical office desk, 152 cm long and 76 cm wide? (2 pts.)
3. A car’s tire makes contact with the ground on a rectangular “footprint” 12 cm X 18 cm. The car’s mass is 925 kg. What pressure does the car exert on the ground? (2 pts.)
4. A lead brick, 5.0 X 10 X 20 cm, rests on the ground on its smallest face. What pressure does it exert? (Lead has a density of 11.8 gm/cm3) (2 pts.)
True or False: Write T if the statement is true. If the statement is False, underline the word or group of words that makes the statement not correct. (5 pts.)
________ 1. Pressure is defined as power per unit area.
________ 2. Atmospheric pressure is pressure in the surrounding air at - or "close" to - the surface of the earth.
________ 3. The unit of pressure is called Planck.
________ 4. When you deal with the pressure of a gas, the medium is treated as a continuous distribution of matter. But when you deal with a liquid at rest, it must be approached as an average pressure from molecular collisions with the walls.
________ 5. A torr is named after Torricelli and is the pressure produced by a column of mercury
Multiple Choice (3 pts.)
1. A gauge is often used to measure the ______________ between a system and the surrounding atmosphere.
a. potential difference
b. pressure difference
c. partial difference
d. kinetic difference.
2. The standard atmosphere is a unit of pressure and is defined as being equal to ___________.
a. 99.325 kPa
b. 100.325 kPa
c. 101.325 kPa
d. 102.325 kPa
3. Pressure in a fluid can be seen to be a measure of energy per unit volume by means of the definition of _____.
a. Work
b. Force
c. Power
d. Speed
