I with questions on using energy, thermal properties and fluids and density

In summary, the conversation is about a student seeking help with test corrections and clarification on incorrect answers. The student also asks for brief explanations to understand the concepts. The content of the conversation includes questions on gauge pressure, atmospheric pressure, temperature change, work, internal energy, absolute pressure, density, translational kinetic energy, heat transfer, and the Bernoulli effect. The student also expresses feeling overwhelmed and asks for help.
  • #1
amandamarie29
4
0
Im working on test corrections that are due tomorrow, and I was out sick for around a month and a half or so. I have been trying to find these in our book, however, our book is pretty much a big hunk of annoying weight that should be used for a campfire. Anyway, I am looking for some help with these problems.. and if you do answer could you please briefly write a sentence or two explanation so i can try and understand? thank you for all of your help! =D

and the answers that i said i had put are incorrect.. that's probably really obvious i just wanted to clarify that... =)

10. A tire of an automobile has a gauge pressure of 30 psi at the top of a mountain, and the air temperature inside the tire is 300K. The atmospheric pressure at the top of the mountain is 0.7 atm. The car is driven down to sea level, where the atmospheric pressure is 1.0 atm and the air inside the tire is heated to 350 K. At sea level, assuming no leaks, the gauge pressure of the tire will be:
A) lower.
B the same.
C) higher.


I put C, but that's wrong and I am not sure why.. i thought pressure increased when temperature increased?11. A barge loaded with lumber and iron ore floats in a lock by a dam ( a closed pool of water like a big swimming pool). If some of the cargo is thrown overboard, the level of the water in the lock will
A) rise, provided it is lumber that is thrown overboard.
B) stay the same.
C) rise, provided it is iron ore that is thrown over board.
D) drop.
E) rise.


I put C here as well. I thought since the lumber would float and the iron ore would sink. so the water would rise when the iron ore sank.20. A perfectly insulated system has work done by it at a rate of 13 W. At what rate is the internal energy of the system changing?
A) 0 W
B) -13 W
C) 13 W
D) 6.5 W


I put A because i was thinking along the lines of it being an isolated system.. and i had to take a guess because i ran out of time.31. The Tonga Trench in the Pacific Ocean is 36,000 feet deep. Assuming that sea water has an average density of 1.04 g/cm^3, calculate the absolute pressure at the bottom of the trench in atmospheres.
A) 1.1 x 10^6 atm
B) 1.1 x 10^8 atm
C) 1.1 x 10^3 atm
D) 1.1 x 10^5 atm
E) 2.1 atm


i don't even know how to start this one..32. How much would a lead brick 2.0 in x 2.0 in x 8.0 in weigh if placed in oil with density p=0.92 g/cm^3?
A) 5.5 kg
B) 0.34 kg
C) 0.48 kg
D) 6 kg


or this one...39. What is the total translational kinetic energy in a classroom filled with nitrogen at 1.01 x 10^5 Pa and 20.7 degrees C? The dimensions of the classroom are 4.60 m x 5.20 m x 8.80 m.

nobody in my class knew how to do this one...5. Which of the following is a TRUE statement?
A) It is impossible to transfer heat from a cooler to a hotter body.
B) The second law of thermodynamics is a consequence of the first law of thermodynamics.
C) It is possible for heat to flow spontaneously from a hot body to a cold one or from a cold one to a hot one, depending on whether or not the process is reversible or irreversible.
D) It is not possible to convert work entirely into heat.
E) All of these statements are false.


I put A because i thought heat flowed from hot to cold17. The Bernoulli effect is responsible for the lift force on an airplane wing. Wings must therefore be designed so as to insure that
A) air molecules move more rapidly past the lower surface of the wing than past the upper surface.
B) air molecules will be deflected downward when they hit the wing.
C) air molecules move more rapidly past the upper surface of the wing than past the lower surface.
D) wings are thick enough to create a significant pressure difference between the top and bottom surfaces of the wings because of the different heights of these surfaces.
E) air molecules will be deflected upward when they hit the wing.


i put A here too.. i was thinking along the lines that more air had to move under the plane to keep it in the air

any help is appreciated.. i feel really stupid and helpless right now =/
 
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  • #2


hey, all my replies were deleted...oh...
 
  • #3


no. 11 - B. use archimedes principle.
 
  • #4


39. use Maxwell-Boltzmann distribution.
 
  • #5


5. D. no engine is 100% efficient. option A is principle of refrigerator.
 
  • #6


17. C. pressure difference.
 

1. What is the relationship between energy and temperature?

The energy of a substance is directly proportional to its temperature. As the temperature increases, so does the energy of the substance. This relationship is described by the first law of thermodynamics.

2. How do thermal properties affect the transfer of energy?

Thermal properties, such as thermal conductivity and specific heat, play a crucial role in the transfer of energy. These properties determine how easily a substance can transfer heat and how much energy is required to change its temperature.

3. How does density affect the flow of fluids?

Density is a measure of how tightly packed the particles in a substance are. In fluids, density affects the buoyancy and flow rate. Fluids with higher density tend to sink and flow slower, while fluids with lower density tend to rise and flow faster.

4. What is the difference between thermal energy and heat?

Thermal energy is the total kinetic and potential energy of the particles in a substance, while heat is the transfer of energy from a warmer object to a cooler object. Thermal energy can be converted into heat and vice versa, but they are not the same thing.

5. How do changes in temperature affect the density of a substance?

Generally, as the temperature of a substance increases, its density decreases and vice versa. This is because as the temperature increases, the particles in the substance gain more energy and move faster, causing them to spread out and decrease the density.

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