B Can a skateboarder ride faster by holding a water bottle?

[Devin-M]

Leg sweep leads to backwards tilting torque:

 

[DaveC426913]

...pushing the body forward below center of mass causes backwards tilting torque.

Which is why your knees are bent and you're in a slight crouch whenever you're riding a board. Because skateboarding is nothing if not moving your body in relation to the CoM.

You don't need a 355g weight; you have a 70,000g weight.

 

[Drakkith]

That’s only if the other foot has friction (standing). On a skateboard the wheels are free to roll forward under the front foot, so pushing the body forward below center of mass causes backwards tilting torque.

I'll meet you halfway with a 'maybe'. There is some friction on the wheels (especially on rough cement/concrete) that may or may not be significant.

 

[russ_watters]

That’s only if the other foot has friction (standing). On a skateboard the wheels are free to roll forward under the front foot, so pushing the body forward below center of mass causes backwards tilting torque.

But again, unlike the leg sweep the force is not directly forward, it's forward and up.

I think at this point we're just going in circles, so I think it is best to end it.