All the world’s energy is in matter.
Gravity, the mother of all energy, never stops, nowhere,

originating from matter’s core, it exerts itself on any matter particle anytime, anywhere in the Universe.

Two bodies are attracted to each other proportionally by the product of their weights, which is, in return, proportional to the square of the distance separating them.

So is how gravity acts.

These two bodies both have available gravitational potential energy and attract each other.
They get closer as the speed increases; a fraction of the potential energy is transformed into kinetic energy proportional to their weight and to the square of their relative speed.
They collide; their kinetic energy cancels out as well as their potential energy, both turning into heat, a degraded form of energy.

Thus aggregated, they form a new mass, slowly cooling down, while somewhere else another mass exerts its force of attraction.

The potential energy of matter is the highest form of energy.

Numerous bodies agglomerate with each other, forming huge masses, the protostars, around which protoplanets revolve.

Heat increases so that a thermonuclear reaction occurs, releasing a new form of energy called the sun. This energy is transmitted to planets through radiation.

Vegetation can grow thanks to this radiation through photosynthesis, and provide wildlife.
Over the millennia, decaying plant matter turned into coal while decaying wildlife turned into oil, both fossil fuels that store the sun’s energy—sons of gravity.

Human beings can exert a physical effort of hundreds of watts through muscular cell metabolism, a process during which glucose in the blood “burns” and is limited by the oxygen transported by the red cells of the blood.

A heat engine, which is a hundred times more powerful, burns oil or coal with oxygen.

Both consume solar energy, the daughter of gravity; one is renewable within human timescales, the other is not.

 

At the time of the pyramids, the only available energy was muscular energy; it was weak but renewable endlessly over the millennia.
Builders had therefore to take the best advantages from it, reducing energetic waste as much as possible, unlike we do today.

To do so, they elaborated work methods based on energy conservation.

The ancient Egyptians left the pyramids as a testimony to their knowledge.
What heritage will we leave with the fossil energies we excessively consume today?

Potential energy:
Let’s take a reader sitting on their chair. They just acquire a potential energy, PE, expressed by the product of the height, h, its mass, m, and the gravitational acceleration constant, g.

PE= mhg

PE is expressed in joules, m in kg, h in m, and g = 9.81 meters/s2.

Laws of inertia:

The reader is bold enough to let themselves fall to the ground. During the short period of time they are falling, they are gaining kinetic energy that is the product of their mass, m, and the square of the fall’s speed, v, all divided by two.

KE = (1/2)mv2

KE is expressed in joules, m in kg and v in meters/second.

Brave, but not reckless, they’d like to know the speed of their fall before touching the ground.

They apply the simplified first thermodynamic law stated by Sadi Carnot, which states:

Energy can neither be created nor destroyed.

So, as they reach the ground, their kinetic energy equals the potential energy they had on the chair.

mgh=(½)mv2

Since m is present on both sides of the equation, m can be canceled from it, so we have:

V=√2.9,81.h
or V = 4,43.√h, where h is in meters and v in m/s.

Or V = 16.√h, h in meters and v in kmph.

Curious, the reader would like to know how long their fall will take:
For linear motion at constant acceleration, velocity is the product of acceleration over time:

v=gt

If v is replaced by g.t in the equality, we obtain:

t=√(2•h/g) or t=0.45.√h

The reader carefully softens their fall, using their muscles as they touch the ground.
By doing so, and due to the law of energy conservation, the kinetic energy is transformed into heat within their body. Anyone who did stepping knows it well!

To put it simply, a reader weighing 70 kg sitting on a 0.6 m highchair acquired a potential energy of 70 x 9.81 x 0.6 = 412 joules, with a time fall before touching ground of 3.43 m/s or 12.35 km/h; the fall only lasted 0.35 s.

If they repeat this little game every second, they will produce a power of 0.421 kw, tiring themselves rapidly!
On the other hand, if they do it every 4 seconds, they will produce 0.1 kw of power and could do that for a whole working day with some practice.

The Archimedes’ principle, which everyone knows, is missing for the physics review to be completed, but this principle was not called or expressed as we know in the pharaohs’ time, under the Fourth Dynasty:

Any object immersed in a liquid is buoyed up by a vertical force equal to the weight of the fluid displaced by the object.

This principle can be translated into dynamics as follows:
A float whose draught is h in meters starts to oscillate if moved upward with a time period t=2.√h, where t is in seconds.

I just explained all the basic notions of physical sciences put into practice by the pyramid’s builders; nowadays, every student who finishes their secondary education is supposed to know that much.