Can a Box Fall Out and Then Back INTO a Moving Truck?

This is one of my official jobs. It’s to take a look at these videos online and figure out if they are real. Oh, don’t worry — -I like my job and I am happy to do it.

Here is the video.

Let’s just be clear about the questionable part. The truck has a box that falls out the back. Is that possible? Is this video even real? Let’s get started.

No Friction, No Air

The physics way is to start with the simplest case. Suppose that this truck is driving along the road. A road with no friction and with no air. The box falls out the back of the truck. But wait! The truck is just a box and the box is just a ball (because it’s easier). Here’s what that would look like.

Yes, that’s exactly what would happen (you can see the code for that animation here). Since there are no horizontal forces on the ball (because of the no air and friction thing) it’s horizontal velocity remains constant.

This alone could make the box fall out of the truck and then back into the truck. Suppose the…