Originally Posted By: paul
the U-bend does not stop it.

it doesnt slow its velocity.

Quote:

its momentum is +4000N

N is not a unit of momentum. So nothing can have a momentum of +4000N.

[quote]
the force going into the turn was -4000N
the force going out of the turn is +4000N

What are these forces acting on? Obviously the force on the mass is in the same direction, both going into the turn and coming out of it. Similarly for the force on the pipe.


Quote:

does you car require double the gas if you only drive around in a circle?

No it doesn't. But our system is frictionless, so the comparable car would require no gas, whether circling or doing a U-turn or bouncing off a spring, or even stopping with regenerative breaking, then accelerating again. Can you say anything that isn't completely misguided?


Quote:

you can spend 1 second , 1/2 second , 600,000,000 years or any amount of time you choose to compress the spring , it will only store the 40N

You're ignoring the part where the force used to compress the spring is also, at the same time, accelerating the sail. Springs don't make forces disappear. We already went through that argument before. If you don't believe me, break open a pen and try pushing the spring. Notice the force is transmitted right through. Use the spring to push something, the thing can be pushed via the spring.


Quote:

the 40N stored force is
40 kg m / 1 second

40N = 40 kg m / s^2
So no, those expressions are not equal.


Quote:

a=40N/1000000
.00004 m/s/s

p=mv
1000000 x .00004 = 40N

Force is not momentum. Velocity is not acceleration. Let's find its momentum after 2 seconds:
p=mv
p=ma*t
1000000 x .00004 x 2 = 80Ns

Let's find its momentum after 1000 seconds:
p=mv
p=ma*t
1000000 x .00004 x 1000 = 40,000Ns


Quote:

from the looks of it it is your physics skills that need a little brushing up.

This really is becoming bizarre. You have just made claims that can be disproved simply by playing with things in the real world. You absolutely havn't got a hope when it comes to physics. Look at all the corrections I made to your lies. Why didn't you try to actually understand what you're saying before saying it?


Just in case you didn't get it the other times:
Force is not momentum
Velocity is not acceleration