Practice Exam I
Fill in the blank
The kinetic theory of gases starts by looking at the change in _____________________ of particles elastically colliding with the sides. Energy that flows at an interface due to a temperature differance is _____________________. The Atomic _______________ number is the numper of protons and neutrons in the atom. The theoretical best performance of a heat engine (Carnot cycle) depends on the ___________________ of the hot and cold reservoir. In a ________________ process now heat flows into or out of the gas. Heat transfer where the mass transports heat by its movement is ________________. The _________________ principle tells us the magnitude of the upward boyant force. The _________________ is the property of a fluid which is thick and requires a pressure gradient to maintain flow in a level uniform pipe.
| State all the laws of thermodynamics. |
| You drink half a bottle of water, cap it, and put it in the refrigerator. When you go back to get it later, the sides of the plastic are sunken in. Use kinetic theory to explain why this happens. |
| Discuss the process of heat transfer by convection. How does it differ from radiation heat flow? |
| State the Bernoulli effect. |
| Why is the molar specific heat different for monatomic and poly atomic gases? |
| What do we mean when we say a refrigerator is a heat engine operating in reverse? |
| What is the volume of a steel ball at 300C if its volume at 600C is 50cm3? |
| An object with density 700 kg/m3 floats in water 1000 kg/m3 and displaces 14 m3 of water. What is the volume of the object? |
| Three hundred grams of water at 75° C is placed in a 100g cup of unknown composition at 20° C. Upon reaching equilibrium, the temperature of the cup and water is 35° C. Determine the specific heat capacity of the cup. |
| A glass of iced water is left sitting out in the kitchen. It contains 100g of ice and 400g of water. Over the next few hours the system absorbs 25 kJ of heat. How much ice melts? What is the final temperature of the system? |
| A power plant uses a 6000C heat source to make steam to drive its turbines and dumps its waste heat into the Great Miami at a temperature of 270C. The plant generates 2 x 1011 J/hr of electricity and dumps 2.4 x 1011 J/hr of heat into the river. How much heat is absorbed at the higher temperature and what is the thermal efficiency of the plant? What is the maximum theoretical efficiency of the plant? |
| What is the rms speed of a helium atom at 500 Kelvin? |
| For the following situations, state if the 1st Law of thermodynamics is violated and if
the 2nd law is violated: A) an ideal gas increases in temperature, has 3J of work done on it by the environment, is colder than the environment, thermal energy changes by 5J and absorbs 2J of heat from the envornment. B) an ideal gas decreases in temperature, has 4J of work done on it by the environment, is colder than the environment, thermal energy changes by +2J and looses 2J of heat to the envornment. C) an ideal gas stays the same temperature, has 3J of work done on it by the environment, is colder than the environment, thermal energy does not change and looses 2J of heat to the envornment. |
| A pipe with 2m2 cross section has a volumetric flow rate of 6 m3/s. The fluid density is 1000 kg/m3. The pipe rises 1m and narrows to 1m2 at position #2. What is the pressure change (p2 - p1)? |
| A bar is 40 cm long, and has a cross-sectional area of 2.5 cm2. The bar transfers 400 J/s between reservoirs at 75 and 20 oC. What is the thermal conductivity of the bar? |
| A monatomic ideal gas, initially at a temperature of 450 K, is compressed isothermally from an initial volume of 65L to a final volume of 25 L. The initial pressure of the gas is 200kPa. Determine |
 | a) the number of moles present |
| b) the initial thermal energy |
| c) the change in thermal energy |
| Krypton, a monatomic ideal gas, with atomic mass of 80.80 amu is at 300 K temperature. What is the rms speed of the krypton atoms? What is the ideal molar specific heat at constand pressure of krypton? What is the thermal energy, Etherm, of 5 moles of krypton at his temperature? |
| Balls are placed randomly into two boxes. For the following configurations, which
one has the highest entropy and which one the lowest? 1) one ball in one box, all other balls in the other 2) all balls in one box 3) haf balls in each box |
| A ball with surface area 4 m2, and emissivity of .82 is at 4000 K and is completely surrounded by an "environment" at 100 K. Consider the "envirnment" to have the same effective surface area as the ball. What is the net radiative heat loss of the ball? |
| A monatomic ideal gas undergoes the process shown on the P-V diagram below. There are 500 moles of gas. |
|
| Calculate the temperature at point B. |
| Find the net work done over one cycle. |
| Which line segment is isoboric? |
| Find Q for the process from C to A. |
