Section: Mechanical Comprehension

36) A concrete beam has a maximum strength of 3,000 psi (pounds per square inch). In an experiment, a 500-pound weight is placed in the center of the beam, and the stress in the beam is measured to be 1,000 psi. If the stresses in the beam continue to increase at the same rate with added weight, how much additional weight can be added to the same location on the beam before the beam will break?

1. 500 pounds
2. 1,000 pounds
3. 1,500 pounds
4. 3,000 pounds

The first 500 pounds generated 1,000 psi of stress in the beam; therefore, 500 more pounds will increase the total stress to 2,000 psi. Another 500 pounds will increase the stress to 3,000 psi, which we are told is the maximum strength of the beam. Therefore, the maximum additional load that can be applied to this beam before it breaks is 1,000 pounds.