Rolling Down a Ramp: Tube of Water vs Dirt - Which is Faster?

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A comparison of a capped tube filled with dirt versus one filled with water rolling down a ramp reveals that water consistently rolls faster, regardless of mass. The primary reasons identified for this phenomenon include the lower rotational inertia of water, which does not spin as much within the tube, leading to less energy loss in rotation. Additionally, the uniformity of water allows it to roll more effectively than dirt. The discussion emphasizes the impact of rotational inertia on acceleration, suggesting that the dirt's tendency to rotate with the tube hinders its speed. Understanding these dynamics clarifies why water outperforms dirt in this scenario.
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I was wondering what rolls down a ramp faster - a tube (capped) full of dirt of a tube full with water. So i tried it and found that the water rolled faster -when it's mass was less then dirts mass and also when it was more. i thought of two reasons for this:
1) the water doesn't spin around in the tube as much so less energy is wasted on rotation.
2)the water is more uniform so it rolls better.

what's the real reason?
Thanks.
 
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well ...

rotational inertia. I assume that te dirt rotates with the pipe, whereas the water doesn't. Higher inertia means less accel with same force.
 

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