Table of Contents
IB Physics: Work, Energy and Power
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Work, Energy and Power
Outline what is meant by work.
Work is defined as the force multiplied by the distance moved in the direction of the force.
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Determine the work done by a non‑constant force by interpreting a force–displacement graph.
If we plot the graph of a graph with displacement (s) on the x-axis and force (F) on the y-axis, we get something like this:
If you find the area under the graph, you would find the total work done.
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State the principle of conservation of energy.
In the nineteenth century, some scientists formulated this principle which said:
“The amount of energy in an isolated system is the same all the time. Additionally, energy may neither be created nor destroyed.”
If you lose energy somewhere, it must be gained elsewhere. E.g. If you drop a ball from a cliff, Gravitational Potential Energy is transformed into Kinetic, heat and other forms of energy.
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List different forms of energy and describe examples of the transformation of energy from one form to another.
Kinetic Energy
I guess anything that is in motion has some sort of kinetic energy. Examples include:
- Running a marathon
- A ball falling off the cliff.
Gravitational Potential Energy.
This is the energy that exists due to the position of the object.
A good example is:
- A man standing on a cliff will have gravitational potential energy.
Chemical Energy
This is the energy in a substance that gives the substance potential to undergo a chemical reaction.
A good example is:
- Chemical Energy in a battery.
Strain Energy
Strain energy is released when the constituent atoms are allowed to rearrange themselves in a chemical reaction or a change of chemical conformation in a way that:
