bridge under fire (easy)

this idea was from draegast playing forts, a physics destroy and protect type of game as i would describe it, it was mentioned in a part of his video that it was kinda like poly bridge under fire, so just imagine the cars are missiles and they are going to destroy each other's reactors. this would be made in like the tutorial so you would not know about like upgrading or steel type of stuff, so you only get wood. anyways, have the car at the bottom cross without the "missiles" hitting the bridge