I don’t know who invented this crazy challenge, but the idea is to put someone in a carved-out ice bowl and see if they can get out. That means the Earth exerts a forward-pointing force back on you, which we call a frictional force. And (2) how hard these surfaces are pushed together, which we call the normal force (N). The normal force is kind of a weird concept for physics newbies, so let me explain. That limit is determined by the static friction coefficient (μ s ).