Question

1. A child is drinking a liquid with a straw. Which of the following statements is true? Why?

a. Longer Straws work better because the pressure is larger deeper down.

b. The pressure inside the straw depends on the viscosity of the liquid.

c. The pressure in the straw is reduced and the liquid is pushed upward by atmospheric pressure on the surface of the liquid.

2. If you hold a light tissue in your hands and gently blow across its top, the tissue will rise slightly because of what? Why?

a. Blowing across the tissue removes all of the air, and then the air below the tissue pushes the tissue up.

b. Collisions of the moving air with the tissue cause it to rise.

c. The pressure of moving air is less than that of static air.

3. Even though your car weighs several thousand pounds, it can easily be raised above your head by a pneumatic lift at the service station by a small motor pumping fluid through a pipe. This is an illustration of? Why?

a. Pascal's Principle

b. Archimedes' Principle

c. Newton's 3rd Law

4. Two identical objects, one light colored and the other dark colored, are the same elevated temperature, 50?. You now place them in a dark, much cooler room. Which object will reach the room's temperature first? Why?

a. The dark colored object

b. Both reach room temperature at the same time

c. As strange as it seems, neither object will ever reach room temperature because energy conservation prevents loss of energy

5. The circulatory system, lake inversion, shore breezes, and heating systems are all examples of what type of heat transfer? Why?

a. Convection

b. Radiation

PLEASE ANSWER WHY ON ALL QUESTIONS!

Answer 1

1. C

The pressure in the straw is reduced and the liquid is pushed upward by atmospheric pressure on the surface of the liquid.

Fluid moves from a region of low pressure to a region of high pressure. Thus when the pressure in the straw is reduced, the liquid rushes to a region of high atmospheric pressure towards the surface of the liquid.

2. C

The pressure of moving air is less than that of static air.

According to Bernoulli's principle, an increase in pressure energy of fluid is accompained by decrease in kinetic energy of fluid. Thus moving air has a lower pressure energy than static air, which causes the tissue to move up when blown across with air

3. A

Pascal's Principle

Pressure applied to any part of the fluid is transmitted to each part of the fluid. Pressure is the ratio of force to area. Thus if a large force is to be obtained, the area of the fluid si decreased which gives rise to magnified forces capable of lifting large weights.

4 A

The dark colored object

Dark bodies are not only perfect absorbers of heat, they are also perfect emitters of heat. Thus in a dark room, a dark body will reach the room temperature earlier.

5. A

Convection

In the daytime, the land and water bodies are heated by conduction. Due to this, the air above this region becomes hot and rises, which is then filled by cooler air givin rise to lake inversion, sea breezes etc. This occurs due to convectiion heat transfer.