Among other things firewood, carbon, and - depending how far you go back in time - petroleum. Also some water and wind energy.
In theory, energy can be transferred multiple times in various forms such as from one object to another or between different forms like potential and kinetic energy. However, with each transfer, some energy may be lost as heat due to inefficiencies in the system, so there is a practical limit to the number of times energy can be transferred before it becomes too low to be useful.
Alessandro Volta tried many times to create a battery before being successful. It's estimated that he conducted over a thousand experiments before inventing the voltaic pile, the first modern electric battery, in 1800.
There was not that much of a usage before but in modern times people are using too much energy. An example is large houses. You look behind the house and you see at least 2 huge air conditioners. It is using too much energy.
The energy stored in a spring in a pinball machine before it is released is potential energy. When the spring is compressed, it gains potential energy due to the elastic potential energy stored in it. This potential energy is then converted into kinetic energy when the spring is released, propelling the pinball into motion.
Einstein proposed the equation E=mc^2, which states that energy (E) is equal to mass (m) times the speed of light (c) squared. This equation demonstrates the equivalence of mass and energy and is a fundamental concept in modern physics.
Most people lived in Europe and Asia.
The used to push them with the help of logs
Because there was no electricity for electrical stoves in modern times
Either as illness or the work of demons or some supernatural force.
Energy is much a notion of modern times, so none of the ancient gods will fit in there.
China
food
Red and blue coloured alcohols are the most common in modern times, although mercury was used for a long time before people figured out how toxic it was.
No. People are just as intolerant in modern times as they were back when. Things have changed towards how racists can treat those they despise, but it's still there as it was before.
After WWII people could no longer become samurai, but the devotion of samurai is still used in modern times.
They poured lemonade on the troubled areas.
Yes, some people still worship Egyptian gods in modern times, particularly in the form of modern pagan or Kemetic religions. These belief systems draw inspiration from ancient Egyptian mythology and practices.