You push a heavy crate down a ramp at a constant velocity. Only four forces act on the crate. Which force does the greatest magnitude of work on the crate?
Correct answer: A. The force of friction
- A. The force of friction
- B. The force of gravity
- C. The normal force
- D. The force you are pushing
Explanation
As the crate is moving at a constant speed, the net force is 0. The total of the forces exerted on the crate down the slope is equal to the forces up the slope.Forces down the slope = Pushing force + force of gravityForces up the slope = friction forceSince Forces up the slope = Forces down the slope ∴ friction = Pushing force + force of gravity Hence, friction is the greatest force.
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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