1. What name should be applied to the stress produced at point A in Fig. 103?

2. To what stress are the legs of the table subjected in Fig. 104?

3. To what stress is a boiler seam rivet subjected? (See Fig. 105.)

4. What stresses are produced in the main rod of a locomotive when the engine is working?

5. What stresses are produced in the piston rod of a locomotive when working?

6. To what stress are the stay bolts of a boiler subjected?

7. To what stress are the sheets of a boiler subjected?

8. To what stress does the blacksmith subject a piece of iron when he strikes it a blow with his hammer?

Questions Stresses 191

Fig. 103.

Questions Stresses 192

Fig. 104.

Questions Stresses 193

Fig. 105.

9. To what stress is the boom of a crane subjected when lifting a load?

Material-Testing

1. What makes one substance stronger than another?

2. What is elasticity of a body?

3. Is it possible to twist, bend, or stretch a body? How may each of these actions take place?

4. What is meant by a cross-section?

Problems. Stresses

1. What is the weight supported at A and B in Fig. 101?

2. Two men carry a weight of 20 lbs. on a pole, one end of the pole being held by each. The weight is 2 ft. from one end and 3 ft. from the other. How many pounds does each man carry?

In the following examples, 271,000 is the breaking load.

1. A test piece 8 in. long between marks and 1 1/2 in. square shows an ultimate strength of 40,000 lbs. per square inch. What is the total load required to break it?

2. What is the ultimate elongation in the above test if the elongation of the whole piece is 1/32 in.?

3. The breaking load in a tension test is 300,900 lbs. If the specimen is 1 1/2 in. in diameter, what is the ultimate strength?

4. A bar 8 in. between marks is pulled in a testing machine until it measures 8.125 in. just at the breaking point. What is the per cent of elongation?

5. A piece of boiler plate 16 in. long stretches .0125 in. during a test. What is the per cent of elongation?

6. The unit elongation of a piece in tension is 1/128 in. What is its ultimate elongation?

7. If a cast iron bar 1 1/2 in X 2 in. breaks under a tension of 60,000 lbs., what tension will break a bar of the same material 1 1/4 in. in diameter?

8. A bar of wrought iron 2 1/2 in. in diameter ruptures under a tension of 271,000 lbs. What is its ultimate strength?