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The figure shows three forces applied to a trunk that moves leftward by 3.16 m over a frictionless floor. The force magnitudes are F1 = 5.39 N, F2 = 9.29 N, and F3 = 3.45 N, and the indicated angle is θ = 60°. (a) During the displacement, what is the net work done on the trunk by the three applied forces, the gravitational force, and the normal force? (b) Is there a net transfer of energy to or from the trunk? (c) Does the kinetic energy of the trunk increase or decrease?
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- NCSLv 79 months ago
Welcome to Yahoo!Answers.
Some of this can be answered without the diagram; some can't.
(a) Assuming the floor is horizontal, the work done by gravity and the work done by the normal force are both necessarily zero, since those forces are perpendicular to the direction of motion.
For the applied forces and no friction, the work done is
Wnet = Σ (F*cosΘ * d)
where Θ is the angle between the applied force and the direction of motion.
(b) Yes; there is a net transfer of energy to the trunk.
(c) Yes; the applied forces increase the kinetic energy of the trunk.
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