292 



TRANSPORTATION 



EXPERIMENTS OR DEMONSTRATIONS WHICH WILL 

 HELP ANSWER THE PROBLEM QUESTIONS 1 



Experiment 172. Does steam possess energy? 



Put a small amount of water into a test tube. Push a 

 greased cork stopper into the tube, not too tightly. Hold 

 the test tube in a flame by means of a test tube holder. 

 Keep the test tube pointed away from your body. Do not 

 point it toward any other person. Observe what happens 

 after the water begins to boil. Write your observations and 

 answer the questions. 



_. What change took place in the water as it boiled? What 

 happened to the cork? Why does the steam have a push? 

 How could this push of the steam be harnessed? 



Activity 173. What are the parts of a steam engine and 

 how does it operate? 



A steam engine is a device that harnesses steam and 

 changes the force of expanding steam into mechanical en- 

 ergy. Obtain a model of a steam locomotive like the one 

 shown in Figure 482. If no model is available in your 

 school, use the diagram of a steam engine and boiler 

 (Figure 484). Study it carefully and explain in your own 

 words how the engine works. 



Experiment 174. Where does the power come from in 

 a gas engine? 



Find a tin coffee or syrup can (large size) with a good 

 lid. Make a hole in the side of the can about one inch from 

 the bottom. Attach a piece of rubber tubing to a gas jet and 

 insert the end of the tube into the hole in the side of the 

 can. Make a hole in the center of the lid. Turn on the 



FIG. 482. MODEL OF STEAM LOCOMOTIVE 



gas until it drives the air out of the can. Turn off the 

 gas and hold a lighted match to the gas escaping through 

 the hole in the lid. Stand back and wait. What happened ? 

 Did the exploding mixture of gas and air possess energy? 

 What is the evidence for your answer ? 

 (Teacher demonstration) 



Pour half a tcaspoonful of gasoline into a quart jar. Cover 

 it. After several minutes remove the cover and hold a 

 lighted match to the mouth of the bottle. Record your ob- 

 servations. 



Experiment 175. What does the carburetor of the auto- 

 mobile do? 



^Examine an atomizer used either for a medicinal spray 

 or a perfume spray. What does an atomizer do to a liquid? 

 Discover how the atomizer makes this change in the liquid. 



1 See workbook, p. 104. 



Examine an old automobile carburetor or study Figure 

 483. Take the carburetor apart, if possible, and see if you 

 can discover how it is like the simple atomizer which you 

 have studied above. These questions will guide your study. 



Where does the liquid gasoline come into the carburetor? 



What does the float valve do ? 



To cylinder 



Throttle 

 ~ valve 



Air 



Float valve 

 Liquid gasoline. 



FIG. 483. CARBURETOR 



Where does the gasoline go from the float chamber? 

 What does the needle valve do ? 



What is mixed with the gasoline vapor in the mixing 

 chamber ? 



FIG. 484. STEAM BOILER AND ENGINE 



How does this get into the carburetor? 



Where is the choke valve and what does it do ? 



Where is the throttle valve and what does it do? 



Record your notes and complete the following statements. 



Atomizers and carburetors are used to change to 



In the carburetor is mixed with vapor to 



form the explosive mixture which goes to the cylinder. The 



valve is on the air inlet. The valve controls the 



and mixture going to the cylinder. Liquid gaso- 

 line is kept at a definite level in the chamber by the 



valve. 



Experiment 176. How is the gas and air mixture ex- 

 ploded in the cylinder of an automobile engine? 



Secure a can of about a gallon capacity, with a tight 

 fitting lid. A smaller size will work. Make a hole in the 

 side and insert an old spark plug taken from an automobile. 



