Work and energy Energy is never created nor destroyed; it just transforms from o
ID: 1393516 • Letter: W
Question
Work and energy Energy is never created nor destroyed; it just transforms from one kind to another, and from one object to another. This tutorial introduces you to energy conservation and its connection to the concept of work. 1. Introduction to work, kinetic energy, and potential energy Here are some basic definitions, phrased informally: Kinetic energy = The energy something has because of its motion. The heavier or faster something is, the more kinetic energy it has. Gravitational potential energy = The energy ''stored'' in an object because it's been lifted. The energy is ''potential'' because it has the potential to turn into kinetic energy-for instance, if the object gets dropped. The heavier or higher an object is, the more potential energy is stored up. A. A child pushes a loaded wagon up a hill, starting slowly but gradually getting faster and faster. Is the wagon gaining kinetic energy, gravitational potential energy, both, or neither? Explain. B. Suppose the wagon gains a total of 50 joules of energy. (A joule, like a calorie, is a unit of energy.) According to energy conservation, energy is never created nor destroyed. But the wagon just gained 50 joules! Does this scenario contradict conservation of energy? Explain why or why not. C. When you say something like ''the jogger just burned 100 calories'' of energy, what does that mean? Where exactly do those 100 calories come from? In other words, what form of energy is depleted by 100 calories? Hint: This is as much a biology or chemistry question as it is a physics question. D. Roughly speaking, work is the mechanical energy-the kinetic and potential energy-given to an object by exerting a force on it. How much work did the child do on the wagon?Explanation / Answer
A. as the wagon is gaining speed , hence kinetic energy increases
as the wagon is travelling up on the hill , it is gaining gravitational potential energy due to increase in height.
B.
no. the work has been done on the wagon to increase its kinetic and gravitational force by applying force. this work done appears as the 50 J increment . hence conservation of energy rule still hold true.
C.
by burning it means that the jogger has done work of 100 calories or jogger has lost 100 calorie by doing work from his body. here the chemical energy stored in the body converts to useful work.
D.
workdone on wagon = increase in KE + PE = 50 J
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