Physical Science 103Work / Heat Review Questions
1. Let’s imagine you have a super-duper microscope that would allow you to see a substance at the molecular level. Compare the behavior of the particles of a hot liquid in a container vs a cold liquidin another container. Now, mix the two liquids and describe the interaction of these liquids at the particle level.
2. On a hot summer’s day after working in the garden I often sit in front of a fan to cool myself since I do not have air conditioning. Explain the fact that the moving air cools me down on a hot sweltering summer’s day.
3. The specific heat of granite is 890 J/kg oC. You start the experiment by placing a 35.00 g piece of granite into a hot oven. After heating for 15 minutes, you place the granite into a Styrofoam cup containing 85.0 mL of water at 22.0 oC. The temperature of the water rises to 32.0oC. What was the temperature of the stove when the piece of granite was placed in the oven? (Q = m C T)
(Cwater: 4190 J/kg oC)
4. Using the Kinetic Molecular Theory describe the changes that occur at the particle level when a metal rod is heated at one end in a fire until the opposite end becomes hot to the touch.
5. My wife noticed that when she puts perfume on her neck it makes her skin feel cool. She is an English teacher, so please explain her observation in scientific terms.
6. A balloon is filled with air and its circumference measured with a tape measure. It is then cooled in the freezer for an hour. You then remove the balloon from the freezer and immediately measure the circumference again. What would your measurements show? Use the Kinetic Molecular Theory to explain the changes in the balloon when placed in the freezer.
7. Why do your feet feel cooler on a tile floor than on a rug?
8. Equal masses of zinc and lead are placed in the freezer and then allowed to warm on the counter top. Lead warms up to room temperature faster than the piece of zinc. Compare the specific heat capacities of the two metals in order to explain these observations.
9. Two equal masses of aluminum and copper are dropped from
a very tall building and allowed to impact the ground. Aluminum has a specific heat capacity three times that of copper. Compare the two metals for the following:
a. The GPE when released.
b. The KE at the point of impact.
c. The temperature after impact.
10. Compare the work and power for the following situations:
a. A 85.0 kg person climbs a 2.50 m set of stairs in 4.50 s.
b. The same person climbs another set of stairs in 3.50 s.
c. A 100.0 kg person climbs the set of stairs in 4.50 s.
11. In (a) above, how many flights of stairs would be required to “ burn” off a 175 Calorie candy bar?