Momentum of the Undead First, we're going to assume that you've been chased out to the middle of a frozen, frictionless lake. Unfortunately for you, there is a zombie coming from another direction. Even worse, this is a smart zombie, who figures that he can run at a 30 degree angle to catch you. Once you hit the ice, you are running at 5 m/s, and the zombie lumbers behind you at 2 m/s. Even more bad news... The zombie moving towards you trips at the edge of the snow, launching himself at 3 m/s. Your best bet is to push the zombie in a way that traps it on the lake, while you slide off to safety. I would suggest doing this by pushing the zombie away, the direction that it is sliding, in as little time as possible. If you can avoid the teeth, pushing with a force of 3 times the mass of the zombie over one second will do the trick. This would be around 200 Newtons of force, depending on the mass you choose to represent the zombie. Any less time touching the undead, the better.Unfortunately, this means that if you push for only 0.5 seconds, then you have to push with 6 times the mass of the zombie, which is quite a bit of work, especialy without friction... As you can see, you end up sliding off at a 102 degree angle off of your initial direction, at about 3.16 m/s. This is all assuming that you an the zombies have similar mass.