PHYS 162 Solar Energy

Old Exam # 1

This exam was given by me in a previous course. It has topics on it we haven’t yet discussed in this course. Use this exam as a study aid to help you get acquainted with my type of exams.

Type of Energy Abbreviation

A. Kinetic Energy KE

B. Gravitational Potential Energy GPE

C. Chemical Potential Energy CPE

D. Elastic Potential Energy ElPE

E. Potential Difference or Voltage V

G. Electromagnetic Radiation: ER

H. Heat or Thermal Energy H

1. Describe the energy transformations that occur during the following activities and processes.

(12 Points)

A. A bunghee jumper jumping off a platform.

B. A car driver is applying friction to the wheels by using the brakes The car slows down to a stop.

C. A rocket blasting off into space.

D. A waterfall that has an electric generator located at the bottom of the waterfall.

2. Indicate which of the following units are energy (E), power (P), or neither (N). (10 points)

Kilowatt-hour______	Calorie/Hour_________
Joule __________	kJ/m2____________
Calorie________	Watt _____________
BTU__________	BTU/hour_________
kilowatt -kg_______	Joule/sec_____________

3. The Willamette hall atrium height to the third floor is around 10 meters. What is the shortest time a 175 LB (mass = 80kg) person could run the stairs if the power output of that person is 400W. ( The total Potential Energy Change is 8000 J) (10 Points)

4. The hot water you use during a shower needs an average of 4.7 kW-hrs of electrical energy to be heated. Mount Hood has an elevation around 3km. Determine how far up or how many times you would have to climb Mt. Hood to gain enough Gravitational Potential Energy to equal the energy used in taking the shower ( Approximate your mass to be 60kg.) (G.P.E. = mgh) (15 Points)

5. Sketch a flat plate collector that will be used to heat water for domestic use. Be sure to label the parts and make a brief statement on the material used and why it is an important part of the collector. (15 Points)

6. Typical numbers for the falling mass turning the generator which lit the light bulb were:

Falling Mass = 1 kg Bulb Current (I) = .2a
Distance it Fell = 1 meter Bulb Voltage (V) = 8.0v

Time mass was falling = 2.0 seconds Time Bulb was on = 2.0 seconds

Energy from the falling mass turning the generator = mgh. The energy used by the bulb = Pxt, where P is the power delivered to the bulb (P=IxV). What is the efficiency of this miniature power plant? (10 Points)

7. What is the maximum efficiency you can get from an automobile if the temperature inside the cylinders of a car engine burning gasoline is approximately 12500K and the air temperature outside is approximate 3000K ( approximately 750F). (10 Points)

8. When applying passive solar to space heating, designers try to build a room using materials that have a high specific heat. What is the desirable effect of using these high specific heat materials in a room that receives allot of sunlight? ( 10 Points)

9. State the Second Law of Thermodynamics .(5 Points)

10. Briefly describe the three methods that heat energy is transferred from two sources that are at different temperatures. ( 6 Points)

11. A pane of glass reflects 5% of the incident light, and absorbs 6%. The amount of light that is transmitted is ______% ( 5 Points)

12. What happens to the light energy that was absorbed by the glass? ( 5 Points)

13.A pyranometer measures what type of solar radiation? (5 Points)

14. What type of radiation is measured with a pyrheliometer? ( 5 Points)

15.Describe or draw the physical difference between a pyranometer and a pyrheliometer. (5 Points)

16. What methods of heat transfer are controlled by using fiberglass insulation? (5 points)

17. On a cold day, a piece of metal feels much colder to the touch than a piece of wood. This is due to what physical property?