Now find the pressure exerted on your chest if you pushed with just the tip of your finger with the same force. Assume the tip of your finger is a circle with a radius of .5 cm. (255,000 N/m² = 37 lb/in²) (Area of circle = pir²)

How much more pressure was exerted with the fingertip compared to the whole hand? (51 times)

2. Consider a cylindrical stick being used to press against the ground. That means the surface of contact is a circle. What would happen to the pressure if the size of that circle were decreased by a factor of 4? (Increase by a factor of 16) You must show why!

What would happen to the pressure if the circle were increased by a factor of three? (Decrease by a factor of nine)

What is the relationship between pressure and area?

3. How much mass of saltwater is contained in a one cubic meter tub? rsw = 1.03(10³) kg/m³. (1030 kg)

How much does that much water weigh in pounds? (2276 lb)

Mercury is the densest liquid. In fact, a cubic meter of mercury would weigh 30,000 pounds! Find its density if 1.7 kg fits into a cubic container with sides measuring 50 centimeters. (13.6(10³) kg/m³)

A hollow cube is filled with air with a certain pressure. What would happen to the density of the air inside if the sides were decreased by a factor of 1/3? (Increase 27 times)

What would happen to the density of the air if the sides were increased by a factor of two? (Decrease by a factor of 8).

What is the relationship between density and the sides of that cube?

4. What are the two main factors that cause the distribution of the Earth’s Atmosphere?

If 50% of the atmosphere is below the altitude of 3.5 miles, and 90% of the atmosphere is below 12.4 miles, how much of the atmosphere is between 12.4 miles and 3.5 miles?

5. Give an example you have encountered in your life that demonstrates pressure. (It can be any type like water or air pressure).

6. Find the force needed to lift a 1000-kg (2201-lb) mass if the mass was .50-m from the fulcrum, and your force was 150 meters from the fulcrum. (33 N)

Find the mechanical advantage: (300)

Even though you are able to lift over 2000 pounds with a little over 7 pounds (33 N), what are you giving up?

Find the force needed to lift the same 1000-kg (2201-lb) mass if the mass was 10-m from the fulcrum, and your force was 1.0 meters from the fulcrum. (98,000 N)

Find the mechanical advantage: (.1)

Compare and contrast the mechanical advantage when it is greater than one and less than one. In other words, what does it mean when it is greater than one, and less than one.

Even though you are using a bigger force to lift the mass, what do you gain?

7. If the input radius is 75-cm, and the output radius is 2.5 meters, find the mechanical advantage of the hydraulic press. (11.1)

Find the force needed to lift 2,000 pounds (905-kg). (798 N)

Find the distance the car moves up if the input distance is .5 meters. (.045 m)

Show that the work done by pushing piston one is equal to the amount of work done by piston two that raises the object.

8. In which picture will the pressure be greatest if the object is 10 meters underwater in both bodies of water?

Find the pressure on a person if he dives to the bottom of a pool that is 10.0 feet deep. (1.3 Atm)

If the person’s eardrums have an area of 2.0 cm2, find the force exerted on the ears. (5.9-lb)

9. How tall would a column of mercury be if the atmospheric pressure was 1.015(105) Pa. Density of mercury is 13.6(103) kg/m³. (.762 m)

How tall would a column of water be for that day? Density of water is 1.0(103) kg/m³. (10.36 M)

In a barometer on a particular day, a mercury column 766-mm high balanced the pressure of the atmosphere. What was this pressure in pascals? (1.02(105) Pa)

Explain why a super vacuum pump can only draw water 10.3 meters up a straw on a typical day.

10. What does the buoyant force on a submerged object equal?

Does it depend on the weight of the submerged object, or its volume?

Find how much of a piece of ice is sticking out of the water if the density of ice is 920 kg/m³, and the density of water is 1000 kg/m³. (8%)

A .50-kg block of wood with a volume of one liter (1000 cm³ = .001 m³) is held completely under water. What volume of water is displaced by the wood? Explain why. (1000 cm³)

What is the mass of the water displaced by the wood if the density of water is 1000 kg/m³? (1.0-kg)

What is the weight of the water displaced by the wood? (9.8 N)

How much buoyant force is exerted on the block of wood? Explain why. (9.8 N)

In what direction will the block of wood accelerate when released?

11. A bracelet that appears to be gold is suspended from a spring scale that reads .10-kg in air and .092-kg when the bracelet is immersed in a glass of water. Is the bracelet pure gold if pure gold has a density of 19000 kg/m³? (density = 12500; no)

Is the ratio between the density of water and the submerged object greater than or less than 1 if it sinks?

Is the ratio between the density of water and the submerged object greater than or less than 1 if it floats?

Draw in the water line for the bottom three situations:

12. In what direction will a fluid always move: Low pressure to high pressure, or high to low?

Explain how a vacuum cleaner "sucks" dirt off of the floor.

Would a vacuum cleaner work on the moon? Expain.

How do we use the answer to part one of this problem to breathe air?

If the pressure outside is the same as the pressure inside our lungs, would we be able to breathe? Explain.

13. Explain why a ten foot snorkel tube would not work under water.

Scuba tanks have a regulator so that the deeper the diver goes, the more pressure the tank exerts. Why is this necessary? In other words, what would happen if the tank stayed at atmospheric pressure when the diver was 15 meters underwater experience 2.5 times atmospheric pressure?

What would happen if the regulator went to a shallow setting while the diver was in deep water?

14. Explain why a roof is not "sucked" off by a tornado. Use Bernoulli's principle.

Sometimes tarps are used to cover piles of wood or dirt. Why does the tarp always balloon out when the wind blows over its top?

15. What is the reason behind an airplane wing's design? In other words, what does its design do in order to enable the plane to take off?

Why are hang-gliders extremeley large?

Why don't the wings of a fighter jet have to be as large as a cargo plane's?