I’m all about Falcon and the Winter Soldier– the latest Marvel show on Disney +. Don’t worry, I’m not going to spoil anything serious. I just want to talk about the wingsuit in episode 1. Sam Wilson (Falcon) is in the grip of a hostage situation on a military plane. The bad guys grab their hostage and jump out of the plane in a wingsuit. If you haven’t seen it, these are basically skydiving outfits with extra material between the arms and legs to make wings – hence the name.
The hostage doesn’t have a wingsuit, so they tie it to the back of one of the evil riders. After that, Falcon flies in pursuit and there’s some action stuff – see, no real spoilers.
But really, it’s just a chance to talk about fun physics. So, consider the next two questions. One: How fast can a human fly with a wingsuit suit? Two: What if you had an extra human (a hostage) on the back of a wingsuit sweater?
Let’s start with something simple and then complicate things. (That’s what we like to do in physics.) Suppose you jumped out of a plane and there is no atmosphere. Yeah, that would be super weird, but imagine. In this case, there would be only one force acting on you – the gravitational pulling downward force due to the interaction between you and the Earth. Gravitational force can be calculated as the product of your mass (in kilograms) and the gravitational field (we use g for that). As long as you are approximately 100 kilometers from the Earth’s surface, the gravitational field is approximately 9.8 newtons per kilogram.
What does this constant descending gravitational force do in an airless world? This is where Newton’s second law comes in. It gives the following relation between force and acceleration:
Two important remarks. First, forces and accelerations are vectors. (This is why they have an arrow on them.) This means that the magnitude and management matters. Second, this expression deals with net force (total force). Since there is only gravitational force, you would accelerate downward – your speed would continue to increase as long as you fell. But this is only fall and not wingsuit flight.