# Why does unoccupied cart have so much higher friction?

...or is it other effect? Kinetic energy cap vanishing?

I've built a test setup: six powered rails on the bottom of a 40-block incline of unpowered rail, and a short loop of rail on the bottom.

If I ride in a cart slowly onto the powered rail, it pushes me near the top of the incline, almost all the 40 blocks and after descent back, through the powered rail, the loop and the the powered rail again I get ejected a long distance from the top of the incline, with a plenty of power to spare - as if energy from descent and double pass through the powered rail accumulated.

Now if I push an empty cart onto the powered rail, it goes some 10 blocks up, descends, then goes around the loop, and back, 10 blocks up. The same happens if I push the empty cart down from the top of the incline.

Similarly, if I leave a long span of unpowered track on the bottom of a long incline, I can ride a long way after the descent, but an empty cart stops a short way from the bottom of the hill.

I'd think such a blatant effect would get mentioned somewhere in the wiki. Or am I doing something wrong? Need to release brakes on empty cart or something?

• actually its that empty carts are much lighter compared to occupied carts (with the same friction) Mar 4, 2013 at 9:32
• @ratchetfreak: ...and how would that work? Search for "minecart weight" returns one relevant sentence: "A player in a cart adds significant weight, requiring more power to push." Plus the slope climb height seems completely counter-intuitive (the lighter cart should go higher up the slope).
– SF.
Mar 4, 2013 at 9:51
• @SF. Remember: In the game you are playing rocks float and sand falls. Physics are not something logic in Minecraft. Mar 4, 2013 at 10:52
• @AnderBiguri: okay, but still, is there some resource detailing the mechanics of minecart movement or could someone expand on it? What should I do if I want a minecart (say, with chest) to move the same as with a player? Is there a way to discriminate between minecarts by weight?
– SF.
Mar 4, 2013 at 11:50
• @SF - There is no concept of weight in the game. The code controlling minecarts treats ridden minecarts different from non-ridden minecarts. If you want a minecart to move as far as a ridden minecart, you will need to mod the game. Mar 4, 2013 at 20:04

It's not to do with friction, it's to do with momentum. An occupied cart is heavier, therefore has much higher momentum when accelerated to the same speed.

That having been said, Minecraft physics is only loosely modelled on the real world, so I could almost make up anything here. Essentially, it behaves that way because it does.

• ...so how can I get carts to move further? Will a cart with full chest move further than one with empty chest?
– SF.
Mar 4, 2013 at 13:00
• @SF. I don't know if there's that much granularity in the weight system, but it looks like you have the setup to do a good test! Mar 4, 2013 at 13:01
• That's actually at least somewhat accurate. The effect of friction on your speed is a function of surface area and said speed, squared; momentum is a function of speed and mass. The heavier cart moving at the same speed will lose less momentum because it suffers the same amount of friction but has more mass to affect. Mar 25, 2013 at 12:27

Look at it from a gameplay point of view. Lets say you were to accidentally push your cart down a hill or on a powered rail and it zooms off down the endlessly long track you just built to who knows where. Now you're stuck walking all the way down the tracks to get it back.

Minecraft isn't exactly realistic game so there's no need for real world physics to be involved, as fredley duly noted. This is more than likely a game mechanic that makes it more convenient for the player. An unmanned cart can't roll away because is quickly comes to a stop, allowing you to recover it. As a game designer you can bend logic for the sake of making something better, because game aren't simulations of real life. What's the fun in that?

As a side note a manned minecart carries more momentum yet it requires the same amount of force to accelerate it on a powered rail. And on a slope a manned cart accelerates faster (defying inertia), so I highly doubt that they were thinking of physics when they added this mechanic to the game. Please correct me if I'm wrong.