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When several external forces act on an object at once, how is the net work on that object defined?
AThe average of the works done by each force
BOnly the work done by whichever force is largest
CThe work from the applied force, ignoring friction
DThe sum of all the works, equal to work by the net force
Answer & Solution
Correct answer: D. The sum of all the works, equal to work by the net force
1. Net work is defined as the sum of the work done by every external force acting on the object.
2. This total is the same as the work done by the single net external force, since work done by the net force accounts for all the individual contributions together.
3. Taking an average of the individual works, or looking at only the largest or only the applied force, would ignore the contributions of the other forces present.
4. Only summing every force's contribution correctly matches how net work is defined.
_Source: OpenStax College Physics (CC BY 4.0), Ch 7 "Work, Energy, and Energy Resources", section 7.2 Kinetic Energy and the Work-Energy Theorem_
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