A Porter carries a 25 kg suitcase a distance of 1 km. Explain why the Porter does no work
1 answer:
The Porter does no work because the force applied is perpendicular to the displacement
Explanation:
The work done by a force applied to an object is given by:
where
F is the magnitude of the force
d is the displacement
is the angle between the direction of the force and the displacement of the object
From the formula, we notice that:
- The work done is maximum when the force is parallel to the displacement (because )
- The work done is zero when the force is perpendicular to the displacement (because )
In this problem, Porter is carrying the suitcase: this means that the force he is applying is upward (to balance the weight of the suitcase, pulling down), while the displacement is in the horizontal direction: therefore, force and displacement are perpendicular, so the work done is zero.
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b ) 0.91 · 3000 = 2730 m
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