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A number unrelated (mostly) to the kinetic energy is the power expended by the engine to keep it moving against air friction and surface friction. … The engine could be expending 10 kW = 10 kJ per sec to maintain a kinetic energy of 380 kJ. It is apples and oranges. …

Editing with additional requested info: The formation of hydrogen from liquid water represents a definite amount of chemical energy. … You just have to convert the L/min flow rate into the equivalent energy. …

It's better to simply study the laws of conservation of momentum and energy, including statics and dynamics, to allow one to analyze any mechanism. …

The Poynting vector $S=E×B$ (up to a factor depending on units) describes the direction of energy flow out of the system, and would be non zero in your case. … The point is that in electromagnetic fields, force and momentum and energy can be non obvious. You can be doing work without matter moving if the fields are …

As of 2019, it's arguable the Joule has a more fundamental definition than the kg, A Joule is the unit of energy such that Planck's constant takes the exact value: $$ 6.62607015 × 10^{-34} \, \mathrm{Joule …

Because momentum must be conserved. A mass $m$ moving with velocity $v_i$ has a momentum $p=mv_i$ prior to the collision. If both objects were at a dead stop after the collision, then $p=0$, which do …

So there is no "infusion" of energy necessary to the system (of asteroids),* and the system's energy before and after is the same. … It simply has a new available state with much lower potential energy and much higher kinetic energy, but the same total energy. …

A planet like Earth is composed of matter, forming a gravity well based upon the total energy content $M$. … Since the total radiative energy is still $M$ and should form the same gravity well, why is the radiative energy able to escape, when the mass energy is not? …

A consequence of this is that taking our universe as a whole, energy is NOT conserved in some respects. … One way this is manifest is the cosmic microwave background has lost energy over time. This energy hasn't "gone anywhere;" it's just off the balance sheet. …

The Fat Man detonation which destroyed Nagasaki is said to have released 88 TJ, or 24 GWh of energy, which is pretty small by the standards of modern H bombs, 1-50 PJ or 270 to 13,500 GWh. … And the state's energy usage is at least double what it was in 1945 I imagine, based on overall US trends. …

The atoms are all being moved slightly further apart (on the whole) and experience an increase in electrical potential energy, which adds up over the whole length to $0.5kx^2$. …

Unfortunately neither of those is the correct formula for internal energy. The product $PV$ cannot be the internal energy, because it makes no account for the temperature $T$ of the gas. … Now for an ideal gas, the internal energy $u$ not only depends upon the temperature, it depends only upon the temperature. …

I'm not sure I fully understand the exact device you are showing in the diagram, but as for the principle of moving a magnet through a coil of wire via mechanical energy input – this is how all electrical …

This new ability to cause motion in the future we call potential energy. The way it is quantified (in Joules) also allows us to accurately predict how much motion (e.g. maximum speed) it will reach. …

A short answer is, in any physical process or equation, Energy as an absolute number has no meaning. It is the energy difference between two states or two objects that determines behavior. … For your electrons and protons, the important fact is that the electron has lower potential energy when close to the proton than it does far away from the proton. …