Physics question

[00tec]

Taking your problem as presented, and with your assumption that no other forces (friction, air resistance, etc...) are applied, then the balls would be subject to Newton's first law of motion, also known as the law of inertia. Both objects would maintain their initial velocities (20mph) and neither would ever stop or slow down, as no other forces are acting upon them. This is what Mr. Prena said.

If we slowly step back from the idealized world, the first factor to come into play is force. It takes more force to get the 20 pound bowling ball up to the same velocity (20 mph) then the 15 pound ball. It will therefore take more force to stop the 20 pound ball. This represents the concepts of conservation of energy and momentum. One of the first forces to act against the balls will be rolling resistance with the surface. Assuming the coefficient of friction between both balls and the hard surface is the same, then it will take more exposure to the force of friction over time to make the heavier ball come to a stop. Thus, the heavier ball will roll further.

If you start adding in other factors, such as air friction, or movement up inclined planes, or surface elasticity, you start changing the sum of forces acting on the balls, and you can contrive a situation where either ball rolls farther.

Agree.

If you have 2 identical vehicles, with one containing extra weight (but had the exact same rolling resistance), and you were traveling 60mph, then let off the gas, the momentum of the heavier vehicle carries it further.

[Erni]

Only thing it eventually stopping those 2 masses are gravity (g=9.8m/s^2) when it hit the ground some day.

Now, if those 2 items were thrown in the space without any gravity affecting it, it need reaction of same force to stop them.

Yes, but if they were thrown in space around earth they would need a lot more velocity thsn 40mph to not fall back down.

[davsel]

[JohnnyEgo]

I should clarify that the weight component of friction will mean that the heavier ball experiences more rolling resistance, but the magnitude of this difference will most likely be relatively minor in comparison to the momentum disparity between the two balls. One could do the math on this, but I can't before I have to get my kid to camp.

[ray1970]

JohnnyEgo and 00tec, I think you guys got what I was going after.

The vehicle analogy was a good one. Basically if both objects were traveling at the same speed and all of the forces acting on those objects was the same (wind resistance, rolling resistance, aerodynamics or each object, etc. and the force moving the two objects was removed I was thinking the heavier object would travel farther before coming to a stop.

Thank you all for information.

[MrPrena]

Yes, but if they were thrown in space around earth they would need a lot more velocity thsn 40mph to not fall back down.

Without gravity.
However you are absolutely right. I would not know any empty space which has pure zero gravity within x parsec.

Spacestation has about 94-95% earth'a gravity by doing univ gravity equn.
Even Neptune is effected by suns gravity.
Heck. Even the galaxy is spinning around the center.

[TFOGGER]

African or European swallow?

[Erni]

Ni.

[mb504]

I should clarify that the weight component of friction will mean that the heavier ball experiences more rolling resistance, but the magnitude of this difference will most likely be relatively minor in comparison to the momentum disparity between the two balls. One could do the math on this, but I can't before I have to get my kid to camp.

But he didn't want to use gravity in the original problem, rolling resistance requires gravity to hold the two surfaces together.

[kidicarus13]

You guys obviously have more free time than me.