Wouldn't the second one move since there is a continuous stream of water to propel it forward? Once the lead ball left the trough, there would be no force to act on the vehicle, right? (looks like the trough is not touching the ground)
Science > SolitaryPenguin, so I am just guessing.
I take that back, the water isn't hitting the ground. I am stumped then.
/wanders off to eat cake
Last edited by SolitaryPenguin; 12-23-2008 at 10:31 AM.
Reason: Because I am American
I'm inclined to agree with Oberon on this one. Part of the gravitational energy pulling the lead balls down will transfer into forward motion due to the 45 in #1. #2 on the other hand, though the water is coming out of the hose, the force created is being negated when the water hits the reclaimer.
Dreams are best served manifest and tangible.
INFP, 6w7, IEI
I accept no responsibility, what so ever, for the fact that I exist; I do, however, accept full responsibility for what I do while I exist.
the 'equal and opposite reaction' that would propel the first vehicle is the movement of the lead balls out the back... the water-based vehicle does not have any gross kinetic output because it is a "closed loop"
Am I a bit retarded for thinking that the first one's balls would just roll down that ramp onto the ground?? I don't see how it makes the car move.
Well, when the ball hits the 45 degree ramp, falling down, the ramp will cause the ball's direction to change (from straight down, as gravity pulls it, to partially horizontal), forcing the ball to move away from the back of the truck. Since the momentum of the overall system (balls + truck) must stay the same (ignoring friction losses, etc.), the truck will move forward as the released ball moves back. But it won't move much (assuming the mass of each ball is pretty small compared to that of the truck + balls still in the hopper). Assuming you're the person who has to pick up the balls and reload them into the hopper, you'd be better off just throwing them all away and pushing the truck by hand.