Guardians of the Galaxy Vol 3 Physics: How Big Is This Moon?

Screenshot from the Guardians of the Galaxy Vol 3 trailer.

I have no idea what’s really going on with this scene from Guardians of the Galaxy Vol 3 trailer. But a lack of knowledge can’t stop me from analyzing this motion. Really, in case you haven’t look at my past blog posts this is what I like to do. Take something from a trailer and see what physics I can figure out. So, let’s do it.

When a new trailer comes out, I will watch it several times to see if there is something physics related. In this case, there’s a very short clip showing the Guardians seemingly running on an asteroid or maybe a moon (it really could be anything). However, it seems to be in a low gravitational field. Here’s what it looks like.

Image: Marvel Studios / Disney.

Now for some physics.

Video Analysis

I’m going to look at Star Lord in this motion (pretty sure he’s the one in the yellow space suit). Once he leaves the surface of the asteroid (again, that’s my assumption), there is only one force acting on him — the downward gravitational force. We can calculate the magnitude of this force as the product of Star Lord’s mass (m) and the gravitational field (g). Note, we are NOT assuming that g is equal to 9.8 Newtons per kilogram like it is on the surface of the Earth. Clearly, this is not Earth.

With this single downward acting force, we can write Newton’s Second Law as:

Since both the acceleration and the gravitational force depend on the mass (of Peter Quill), the mass cancels. This means that the acceleration vector is equal to the gravitational field. But the gravitational field just points DOWN. If we break this into x (horizontal) and y (vertical) components, we get:

This is actually pretty important even if it looks simple. First it says that since the acceleration in the horizontal direction is zero, the horizontal velocity should be constant. Second, the vertical acceleration should be constant AND if we find the acceleration, we have a value of the gravitational field.

OK, let’s get some data. I’m going to use Tracker Video Analysis (it’s free and awesome) to get…