Everybody knows the ketchup, the sweat red tomato sauce in glass bottle. People love ketchup and use it every day. One day, there is not enough ketchup to run out of the bottle and it sticks on the bottom, that’s the „ketchup problem.” Now, you have to hit the bottle on the bottom. The bottle has to stay in its position. Now it is inertia time. Velocity of your arm is changing to force, when you hit bottle. Let`s call it force F. The vector of the force F should aim threw the bottleneck. The bottle is not moving because you hold it in your hands. But you do not hold the ketchup. That is the force which sticks the ketchup inside the bottle. If the force F is bigger than the force which sticks the ketchup inside the bottle the ketchup runs out. Mostly, you hit the bottle too much, so all the ketchup shot out on your omelet. That is the “ketchup problem”, the inertia problem in everyday life.