| Nothing | |
| You`ll hear air escaping from the open valve | |
| You`ll see the brakes on the last trailer engage | |
| You`ll see the emergency valve open and release air |
| The more trailers you`re pulling the larger the effect | |
| The rearmost trailer is the most affected | |
| Another name for rearward amplification is the crack-the-whip effect | |
| The longer the trailers you`re pulling the larger the effect |
| Are required when driving a double or triple trailer | |
| Make objects look closer and smaller than they actually are | |
| Make objects look closer and larger than they actually are | |
| Are against the law |