How to stop momentum immediately

In my game I’m going for a tomb of the mask game style, and I’m trying to make a block that stops you mid run, but I don’t know how to get the momentum to stop. If I’m not clear enough, go to level eleven on the game I’m linking to, I’m trying to get the block with the white stuff (glue) to stop his momentum. Please help if you can.

Add a Velocity behavior block (in properties) and set both x & y to 0. This will stop an object from moving.

The game concept you’ve got is great! Plus, it gives me an awesome idea, that I may add to my Tutorials Page!
Complex NPC tracking by using simple techniques.
A block will move around, hitting objects, (that don’t have to be solid, just sending a message or simple collision.) Once the object is stopped, it waits for the NPC which is set to track the block, fast or slow, and once it reaches a certain proximity, the block will go onto track to its next checkpoint, and the NPC will follow it. Simply hook this up to a switch for when something happens, and it needs to come off track!
Coming back on track might be complicated, but the concept itself is really simple! And, this could be expanded to unprecedented levels!