This is a fascinating exercise in making large numbers more meaningful, using physics.

Basically, we’ll look at the chemical energy content in our food, and calculate the speed of a nine-pound-baby (chosen for the sakes of universality and oddity)  with an equivalent amount of kinetic energy (energy of motion).

So, looking on the McDonalds website, let’s take my standard food item of choice- A Big Mac.  McDonalds puts its calorie content at 540Calories. Now, remember- the food industry uses capital-C “Calories” as “kilocalories” so that they don’t have to explicitly admit that a Big Mac contains 540,000 calories of chemical energy.  You may recall from chemistry class that a single calorie is the amount of energy it takes to raise the temperature of one gram of water one degree.

This 540,000 calories is actually an archaic unit- let’s switch over to the SI unit Joules by multiplying by 4.184; yielding that the one Big Mac is roughly equivalent to 2,259,360 Joules.

The equation for kinetic energy is KE = (m * v^2)/2

So our roughly 9ish pound baby- approximately 4ish kilograms, then (divide pounds by 2.2 to get the kilogram equivalent), with 2,259,360 joules of kinetic energy, would need to be moving at:

2,259,360 = (4 * v^2)/2

v = 1062.86 meters per second.

For reference, the speed of sound at room temp in air on the earth’s surface is 334 m/s.

Modern fighter jets cap out at Mach 3 (as in, 3 times the speed of sound.)

Thus, our Big Mac meal, if burned with 100% efficiency as fuel to accelerate the 4kilo baby, would result in our baby going a tad faster than the fastest modern fighter jets can go. At this speed, the baby could circumnavigate the Earth at its equator in

40,075,020 m (the circumference of the Earth) / (1062.86m/s) = 37,704 seconds

As in:

37,704 /60 = 628 minutes

628/60 = 10.5ish hours.

A flight Chicago to Tokyo,  nowhere near the distance the baby travels( a mere 10,160,000m, or one-fourth the distance) takes about 13 hours, for comparison.

That, right there, is the energy held within a Big Mac.

Of course, at higher and higher energy amounts one begins to approach the speed of light, and hence must use Einstein’s more accurate equation for kinetic energy.