[Request] How valid is this stupid sounding Facebook picture?

Woops, I went to sleep too soon.

This question is within my field but you can still ask everyone else. Ok here we go.

From Newton's first law we know that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

Let's take a look at a truck moving on earth, there are a few force acting on it: Friction (from the wind, air, ground...), Gravity and Normal Force. Gravity and Normal Force cancels each other out. So there is no force acting on the car this suggest that a truck will move indefinitely without friction on earth (assuming that the Earth is round enough) unless it's going up hill in which case it will slow down and then reverse or if it meet with a wall... then it will stop. Which mean you don't need any energy at all to keep a car going and as a result any amount of distance will require 0 energy. But! you will still need to speed the car up (the energy required is equal to 1/2 x M x v2 - M is the mass of the car and v is the velocity of the car) but once it's running it will go on forever. Now we know that the car has to move 20 miles (32186.9 meter) a day so its velocity has to be 32186.9/(24*3600) = 0.373 m/s.

Now let's calculate how much this energy is! 1/2 x M x 0.03732, but wait it will have to be close to you heart's energy consumption (or at least in the same order of magnitude) for this facebook post to be correct. so 1/2 x M x 0.3732 = 432000 (that's for just one day), solve for M give us 6.21 million kg (or 6210 metric tons), that's for a 5W heart, but it can go as low as 1.3 which is 5 time less we are still looking at 1/2 x M x 0.3732 = 1 x 24 x 3600, solve for M and it's 1200 metric tons, which is too heavy for any normal or practical truck. And this energy is only needed once!

So with a frictionless truck/car the energy consumption of a heart is too high. WAY too high since that's just one day, but a person may live up to 65 years!

/r/theydidthemath Thread Parent Link - imgur.com