- #1
Ron77
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Hi Folks,
Question on momentum.
I have been talking with someone who is more educated than I, especially in math, but they are saying something that just doesn't make sense to me. I do realize that physics doesn't always make 'sense' so thought I'd ask on here. He said I would need calculus to understand why, but the answer, almost seems intuitive...
Here it is..
He says that both of these will have the same momentum even though one has about 20 times the mass of the other and V is the same.
1) A person laying on their back does a bench press exercise with a real barbell weighing 200 lbs at a certain velocity
2) Another person laying on their back does a bench press exercise at the same velocity, but the resistance is provided by rubber bands that provide 200 lbs of downward tension. (like a Soloflex exercise machine)
I am thinking that number 2 will have almost zero momentum. It seems that no matter how fast you moved your arms, if you stopped, the 10 pound bar with the bands attached would 'stick to your hands' so to speak, but an actual weight would have the tendency to 'keep in motion' moreso.
Also, I read that the definition of momentum is on the order of how hard it is to change the direction of an object. One could easily reverse the direction from traveling upward to downward if tension is provided by elastic materials, but if provided by a real weight with mass, it would be harder to change from upwards, to a downward movement... right?
Thanks,
Ron
Question on momentum.
I have been talking with someone who is more educated than I, especially in math, but they are saying something that just doesn't make sense to me. I do realize that physics doesn't always make 'sense' so thought I'd ask on here. He said I would need calculus to understand why, but the answer, almost seems intuitive...
Here it is..
He says that both of these will have the same momentum even though one has about 20 times the mass of the other and V is the same.
1) A person laying on their back does a bench press exercise with a real barbell weighing 200 lbs at a certain velocity
2) Another person laying on their back does a bench press exercise at the same velocity, but the resistance is provided by rubber bands that provide 200 lbs of downward tension. (like a Soloflex exercise machine)
I am thinking that number 2 will have almost zero momentum. It seems that no matter how fast you moved your arms, if you stopped, the 10 pound bar with the bands attached would 'stick to your hands' so to speak, but an actual weight would have the tendency to 'keep in motion' moreso.
Also, I read that the definition of momentum is on the order of how hard it is to change the direction of an object. One could easily reverse the direction from traveling upward to downward if tension is provided by elastic materials, but if provided by a real weight with mass, it would be harder to change from upwards, to a downward movement... right?
Thanks,
Ron
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