Question

Short Answer
In complete sentences, write the answers to the questions on
the lines provided.
1. If two swimmers compete in race, does the faster swimmer
develop more power?
2. Why is the work output of a machine never equal to the work
input?
3. If a simple machine could be frictionless, how would its IMA and
AMA compare?
4. Compare the effects of a fixed pulley and a movable pulley on the
size and direction of the input force.
5. In a compound machine made up of two simple machines, how is
the work output of the first simple machine related to the work
input of the second simple machine?

Answer 1

1. Not necessarily; power depends on the amount of work done per unit time, so if two swimmers do the same work to cover the course, the faster swimmer produces more power, but if one swimmer does more or less work (because of technique, drag, etc.) the faster swimmer might not have the greater power.

2. The work output of a machine is never equal to the work input because some input energy is always lost to friction, deformation, heat, sound, or other inefficiencies.

3. If a simple machine were frictionless, its ideal mechanical advantage (IMA) and actual mechanical advantage (AMA) would be the same, because no energy would be lost.

4. A fixed pulley changes only the direction of the input force and does not reduce the required force (AMA ≈ 1), whereas a movable pulley decreases the size of the input force (provides a mechanical advantage) but does not by itself change the direction of the input force.

5. In a compound machine the work output of the first simple machine becomes the work input of the second simple machine; in an ideal, lossless case those two amounts would be equal, but in real systems the output of the first is slightly less due to losses.