11.4.2 practice gases and thermodynamics

[Ericka E]

  Finally, it's summer - time for your annual family vacation! This year, you're going to Florida. Not only will you spend a lot of time lounging on the beach, but also you're going scuba diving. This will be so much fun! Or so you thought: Instead of letting you enjoy your free time, your parents insist you keep practicing what you've learned about heat, gas laws, and thermodynamics. Don't despair, though! You won't have to stay in your hotel room all day - you can practice all of these skills while having fun at the beach and in the water. Get ready to dive in!

1. It's a hot day at the beach! You look at your portable thermometer, which says it's 30°C. What is the temperature in Fahrenheit and Kelvin? Show your work. (4 points) 

    For fahrenheit it is 86 (because 9/5 * 30) +32=86. For Kelvin it is 303.15k

2. You're lying on a towel, enjoying the sunshine. You decide to venture down to the water. Ouch, the sand is hot! You run to the water, where you cool your burning feet. (7 points)

A. Why is the water cooler than the sand? (4 points) Sand is a good conductor of heat and water is not.

B. If the sand you ran across has a specific-heat capacity of 835 J/(kg°C), how much energy must be added to a 2-kilogram pile of it to increase its temperature from 40°C to 50°C? Show your work. (3 points) 16,700

 3. All this sun and heat is making you thirsty. You decide to walk down the street to the food stand, to buy some lemonade. As you are walking, you notice big cracks in the sidewalk. What caused them? Describe the situation, using terms from this unit. (4 points) Thermal expansion. The concrete got too hot and expanded.

4. You get to the drink stand, and you are feeling really hot. You order extra ice in your lemonade. (8 points)

A. When you hold the cup of lemonade, your hand quickly feels cold. Use the second law of thermodynamics to describe why your hand will feel colder when you hold the lemonade. (2 points) Because there is no heat on the cup and the heat from your hand is transferring to the cup, so you are feeling the absence of heat from your hand

B. If you wait an hour, what will most likely happen to the ice in your lemonade? Why? (6 points) It will melt because heat will be where it was absent. 

5. At last, it's time to go diving! You load your stuff into the boat and head to an offshore dive site. (10 points)

A. The boat uses a heat engine to move. This is a simple schematic of how a heat engine operates. Describe what this schematic is showing in terms of the laws of thermodynamics. (6 points) If there is supposed to be a picture of some sort I do not see one.

B. If the boat's engine has a heat input of 40,000 J, with 30,000 J exhausted into the surroundings (the heat sink), what is its efficiency? Show your work. (4 points)  .75 or 75%. (because 30,000/40,000=.75)

6. You get to the dive site, put on your gear, and are ready to go under. You check your scuba tank. It is filled to a pressure of about 22,000 kPa (kilopascals) at a temperature of 300 K. The volume of the tank is 25 L. You begin to wonder: If temperature remains constant, what would happen to the volume of gas in the tank if its pressure increased? (11 points) 

A. List and briefly describe the four thermal processes where pressure, volume, temperature, and heat are each held constant. (8 points) it would expand

B. Assume your lungs have a capacity (volume) of 0.5 L at the water's surface. As you dive, the water pressure increases to twice its surface value. What is your lung capacity at this location? (3 points) .25

7. You have a great dive! When you return the beach, you discover remnants of an abandoned building. It is falling down and in ruins. (6 points)

A. Identify the scientific process that explains this situation. (4 points) Nature is taking its toll on the building.

B. How could the building's deterioration be reversed? (2 points) Putting rods and stuff in the concrete to keep it from expanding too much to the point it would break and/or bend, 

Hope this helps :)

their is only a couple of weeks left of school!!!! keep pushing !!!! you got this!!!!