7. What keeps an elevator from moving side to side?

A sheave keeps an elevator from moving side to side and further details in discussed below in detail.

Explanation:

A sheave is a lifter with a grooved edge surface, at the head of the elevator shaft. ... The cords that uplift the car are also joined to a counterweight, which stretches down on the other front of the sheave [and typically estimates about the mass of the car itself plus 42–50 percent of the complete weight it can sustain.

answer; /// i do believe that the correct answer is (d) cooperative play; /// good luck

answer:

d. because dr. laguardia selected a widely used measure, his study generalizes to has strong external validity. external validity has limited external validity. other applications of this measure.

the widely used measure that he applied to his experiment was the benton facial recognition test. it employed on to football players and as result, only players who suffered brain concussions did not pas this test. and although it has an external validity, it is limited because it isn't general to apply to other population.