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(II) A 56.5 -kg hiker starts at an elevation of 1270 $\mathrm{m}$ andclimbs to the top of a $2660-\mathrm{m}$ peak. (a) What is the hiker'schange in potential energy? (b) What is the minimum workrequired of the hiker? (c) Can the actual work done begreater than this? Explain.

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A) $7.7 \times 10^{5} \mathrm{J}$B) $7.7 \times 10^{5}$C) Yes

Physics 101 Mechanics

Chapter 8

Conservation of Energy

Work

Kinetic Energy

Potential Energy

Energy Conservation

Moment, Impulse, and Collisions

Hope College

University of Winnipeg

McMaster University

Lectures

04:05

In physics, a conservative force is a force that is path-independent, meaning that the total work done along any path in the field is the same. In other words, the work is independent of the path taken. The only force considered in classical physics to be conservative is gravitation.

04:30

In classical mechanics, impulse is the integral of a force, F, over the time interval, t, for which it acts. In the case of a constant force, the resulting change in momentum is equal to the force itself, and the impulse is the change in momentum divided by the time during which the force acts. Impulse applied to an object produces an equivalent force to that of the object's mass multiplied by its velocity. In an inertial reference frame, an object that has no net force on it will continue at a constant velocity forever. In classical mechanics, the change in an object's motion, due to a force applied, is called its acceleration. The SI unit of measure for impulse is the newton second.

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(II) A 66.5-kg hiker start…

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(II) A $55-\mathrm{kg}$ hi…

03:59

A 65-kg hiker climbs to th…

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A $65-\mathrm{kg}$ hiker c…

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A 65 -kg hiker climbs to t…

04:42

Find the potential energy …

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(II) A $1.60-\mathrm{m}$ t…

04:25

Potential Energy A 90.0 -k…

03:37

(II) The steps of a flight…

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04:52

An 82 -kg hiker climbs to …

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(II) A 1.60-m-tall person …

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02:52

Okay, So the first part of this problem asks for the change in gravitation potential and she was just given by Delta U equals mass times acceleration due to gravity times, change in height and so mass. Here is 56.5 kilograms. Ah g, of course is 9.8 meters per second squared and a change in height is 26 60. Sosa's final hide, minus initial heights or 26. 60 meters minus 12. 70 meters. And so this gives you 7.7 times 10 to the five jewels or a 7 70,000 jewels. It's not Hey 7 70,000 You'll increase in potential energy in part B. We want the minimum work down, some minimum work done. We'll just be equal to the changing gravitational potential energy. This is assuming no dissipated forces such as fiction. Which brings us to part C. Can the actual work done be greater than, ah can actual work down w B credit than w men? Answer is yes, it absolutely can. This is because of you other forces that that the climber had to overcome which required work to be done and so w. So the minimum work is for the perfect case where there's no fracture, no off air friction, no ground fiction. And of course, no fiction do to Bo do toe joints and other body parts, rum and various end of resistance and stuff like, Well, I guess that is our affection on DSO, right? Lots of dissipated forces that you have to kind of give tract against two to make that God t that goes into the work done. So obviously W could be greater than W main infact it almost certainly will be.

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