How to Use Physics to Lift This Off-Balance Barbell
It’s a fun physics trick, maybe you’ve seen this on TikTok or Instagram. The idea is to present a person with a barbell. On one side there’s a bunch of weight and the other side has very little mass (maybe 1 small plate). When someone tries to lift it, they can’t. The barbell just tips over. It’s awkward and fun — which makes it perfect for an online video.
There are two questions that I’m going to answer. First, why can’t you pick up this barbell? Second, how do you do it? Yes, it’s possible to lift it up with a physics trick.
Rigid Body Equilibrium
You know I’m going to start with some physics — because this is a great physics problem (I might put it on a future test). Suppose I pick up a 10 kg mass and just hold it (maybe it’s one plate). Since it’s at rest, the net force must be equal to zero (the zero vector).
You could replace this vector equation with two scalar equations — one for the y-direction and one for the x-direction. That’s fine.
But there’s something else to consider if you pick up a barbell. Keeping it stationary means that the net force in the x and…
