Suppose that you are trapped on the surface of a frozen lake. The surface is so smooth and ideal that there is no friction at all. You cant make any grip on the ice and no wind is blowing to help you out. You have just a mobile phone with you which has got no reception disabling you to call for help.

How will you plan your escape before you freeze to death on the frozen lake?

You have been told that the floor is ideally frictionless. Thus, all you need to do is throw your mobile phone in the opposite direction and the throw will propel you in the other direction. Since there is no friction, you will be able to glide smoothly to one side even with as little kick as this. This is same as firing a gun.