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Physics   >   Energy

What is Energy?

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In this course, Professor Douglas Halliday (Durham University) explores energy. In the first mini-lecture, we discuss the big picture of energy, looking at types of energy, key principles, and units. In the second mini-lecture, we consider changes in energy by looking at examples of various energy exchanges involving kinetic and potential energy, heat, electrical energy, etc. The third mini-lecture introduces the concept of the conservation of energy and works through four related examples. In the fourth mini-lecture, we discuss the concept of work in greater detail and go through a couple of examples. In the fifth mini-lecture, we introduce the concepts of power and efficiency, working through some examples and looking at how to improve the efficiency of a system.

What is Energy?

In this mini-lecture, we give an overview of what energy is, focusing in particular on: (i) different types of energy; (ii) closed systems and energy conservation; (iii) the definition of energy in physics and the SI unit of energy (the Joule); (iv) converting energy into usable forms; and (v) the details of thermal energy, mechanical energy, electrical energy, mechanical energy, and natural sources of energy.

Cite this Lecture

APA style

Halliday, D. (2022, January 14). Energy - What is Energy? [Video]. MASSOLIT.

MLA style

Halliday, D. "Energy – What is Energy?." MASSOLIT, uploaded by MASSOLIT, 14 Jan 2022,

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Prof. Douglas Halliday

Prof. Douglas Halliday

Durham University