GEND 112 Exam 2: Dynamics and Thermodynamics
Possibly useful equations or constants: q = mC∆T F = ma Cwater = 4.186 J g-1K-1 Cice = 1.99 J g-1K-1 Csteam = 2.05 J g-1K-1 Heat of fusion for water/ice = 334 J/g
Heat of vaporization of water = 2256 J/g K = oC + 273

1.) A 10kg box is sitting on the ground. Person A is pushing down and to the right at a 60 degree angle to the floor with a force of 35N. Person B is pushing down and to the left at a 35 degree angle to the floor with a force of 25N.
a. Draw a free body diagram of this situation (5 points)

b. What is the magnitude of the Normal Force? (10 points)

c. What is the net force and acceleration (please do not forget to include direction) in the dimension that is horizontal, or parallel to the floor? (10 points)

2.) According to the Kinetic Molecular Theory, what is temperature actually measuring? (8 points)

3.) Water has a boiling point of 373 K, and butane has a boiling point of 313 K.
a. Which would have stronger intermolecular forces? (5 points)

b. Which should have a higher heat of vaporization, or latent heat? (5 points)

4.) I put a 150g metal sample with an initial temperature of 400K into 300g of water with an initial temperature of 293K. When it reaches thermal equilibrium the final temperature is 300K.
a. What law of thermodynamics tells me about thermal equilibrium? (5 points)

b. If the metal is the system, is it going through and endothermic or exothermic process? (5 points)

c. What is the specific heat of the metal? (11 points)

5.) My beloved goldfish, Xerxes the Mighty, has become frozen in his outdoor bowl during a surprise cold snap. The ice is currently at a temperature of -15 Celsius. (parts a-g)
a. I get my hair dryer out to melt the ice and hopefully revive Xerxes. How much heat do I have to apply to the ice to bring it to water at 20 degrees Celsius? (11 points)

b. What does the second law of thermodynamics tell me about the heat that is actually produced by my hair dryer? (compare to part a) (5 points)

c. If I define my system as Xerxes, and hold my cold little buddy in my hands, what is the sign of heat for Xerxes and what is the term used to describe this? (5 points)

d. If I am the system, what is my sign of heat, how do I feel to Xerxes and what is the term used to describe this? (5 points)

e. Thankfully Xerxes has survived and is now swimming in his tank with no lid on top. What type of system is his tank? (5 points)

f. If my hairless cat from the last test keep trying to eat Xerxes and I put a glass lid on his tank to seal it, what kind of system do I have? (5 points)

g. What is the name of my hairless cat from the last test? (5 bonus points)