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A person exerts a constant force of 75.0 N at an angle 35 degrees below the horizontal and pushes a lawn mower 25.0 m on level ground. How much work does the person do on the mower?
A1875 J
B1536 J
C1225 J
D859 J
Answer & Solution
Correct answer: B. 1536 J
1. Work is W = F d cos theta.
2. Substituting the given values, W = (75.0 N)(25.0 m) cos(35.0 degrees).
3. The product of force and distance, 75.0 N times 25.0 m, is 1875 N*m.
4. Multiplying by cos 35.0 degrees, about 0.819, gives W = 1536 J.
5. 1875 J is the force-times-distance product left unmultiplied by the cosine factor, and 1225 J and 859 J come from using the wrong angle or an incorrect cosine value.
_Source: OpenStax College Physics (CC BY 4.0), Ch 7 "Work, Energy, and Energy Resources", section 7.1 Work: The Scientific Definition_
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