# Potential Energy and Conservation of Energy

## EXERCISES And PROBLEMS

EXERCISES And PROBLEMS ssm Solution is in the Student Solutions Manual. WW’W Solution is available on the World Wide Web at: http://www.wiley.com/college/hrw ilw Solution is available on the Interactive Learning’Ware. Determining Potential Energy Values 1E. What is the spring constant of a spring that stores 25 J of elastic potential energy when compressed by 7.S cm …

## REVIEW & SUMMARY

REVIEW & SUMMARY Conservative Forces A force is a conservative force if the net work it does on a particle moving around every closed path. from an initial point and then back to that point. is zero. Potential Energy A potential energy is energy that is associated with the configuration of a system in which a conservative force acts. …

## Sample Problem

Sample Problem A circus beagle of mass m = 6.0 kg runs onto the left end of a curved ramp with speed  height Yo = 8.5 m above the floor. It then slides to the right and comes to a momentary stop when it reaches a height  from the floor. SOLUTION: A Key Idea to get us started is …

## Sample Problem

Sample Problem Package of tamale slides along a floor with speed . It then runs into and compresses a spring, until the package momentarily stops. SOLUTION: A starting Key Idea is to examine all the forces acting on the package, and then to determine whether we have an isolated system or a system on which an external force is …

## Power

Power Now that you have seen how energy can be transferred from one form to another, we can expand the definition of power. There it is the rate at which work is done by a force. In a more general sense, power P is the rate at which energy is transferred by a force from one form to …

## Isolated System

Isolated System If a system is isolated from its environment, then there can be no energy transfers to or from it. For that case, the law of conservation of energy states. We discussed a special situation for isolated systems-namely, the situation in which non conservative forces (such as a kinetic frictional force) do not act within them. In …

## Conservation Of Energy

Conservation Of Energy We now have discussed several situations in which energy is transferred to or from objects and systems, much like money is transferred between accounts. In each situation we assume that the energy that was involved could always be accounted for; that is, energy could not magically appear or disappear. In more formal language, we assumed (correctly) …

## Sample Problem

Sample Problem A food shipper pushes a wood crate of cabbage heads (total mass m = 14 kg) across a concrete floor with a constant horizontal force F of magnitude 40 N. (a) How much work is done by force F, and what system does it do the work? SOLUTION: One Key Idea is that  holds here: The …

## Sample Problem

Sample Problem The giant stone statues of Easter Island were most likely moved by the prehistoric islanders by cradling each Statue in a wooden sled and then pulling the sled over a runway consisting of almost identical logs acting as rollers. SOLUTION: One Key Idea is that we can calculate the work done with. Here d is the …

## Friction Involved

Friction Involved We next consider the example. A constant horizontal force F pulls a block along an x axis and through a displacement of magnitude d, increasing.               By experiment we find that the block and the portion of the floor along which it slides become warmer as the block slides. …