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Work

Work transfers energy to a system through the forceful manipulation of its state. Do some work on yourself to master this fundamental mode of energy transfer.

Work Done by a Constant Force

What is the minimum amount of work in Joules that a 60 kg man must do in order to climb up a tree house that is 3 meters high?

Details and assumptions

  • The acceleration of gravity is \(-9.8\text{ m/s}^2.\)

A man who is standing on a ladder vertically lifts a book of mass \(3\text{ kg}\) with a rope at a constant speed. If the change in the book's height is \(7\text{ m},\) how much work did the man do on the book?

The gravitational acceleration is \(10\text{ m/s}^2.\)

A weight lifter is bench-pressing a barbell whose weight is \(650\text{ N}.\) He raises the barbell vertically by \(0.60\text{ m}\) above his chest with a constant velocity. How much work did the weight lifter do on the barbell?

A box with mass \(100\text{ kg}\) is on the flatbed of a truck which is moving with an acceleration of \(a=1.5\text{m/s}^2\) along the positive \(x\)-axis. The box does not slip with respect to the truck. If the displacement of the truck is \(s=35\text{ m},\) what is the total work done on the box by all of the forces acting on it?

A man is pulling a sled on a icy road. The total mass of the sled is \(50.0\text{ kg},\) and the man exerts a force of magnitude \(1.20 \times 10^2\text{ N}\) on the sled by pulling on a rope. At a distance of \(13.5\text{ m}\) from the starting point, the man releases the rope, and the sled stops at a distance of \(18.2\text{ m}\) from the starting point. If the friction force between the ice and the sled is \(45.0\text{ N},\) how much work did the friction force do on the sled?

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