FORUM FUN FEATURE!! Tough Test 6 - Page 3

Nerak936 · 08-09-2004

Quote:

Originally Posted by Bumper

Truth can exist on many levels, grasshopper.

Ya know... when I rub my hind legs together, it does make a funny sound.....

**Bumper** · 08-09-2004

Quote:

Originally Posted by Nerak936

Ya know... when I rub my hind legs together, it does make a funny sound.....

As opposed to rubbing your front legs together???

Nerak936 · 08-09-2004

Quote:

Originally Posted by Bumper

As opposed to rubbing your front legs together???

Yup. You should see me run. I'm really really really fast!!

**Jesus** · 08-10-2004

Quote:

Originally Posted by Beachwolverine

Although Bumper agrees, I will disagree with your reasoning (I agree with the result). Respectfully of course. I believe you would be right if the rope had weight. BUT since the rope is weighless, monkey and weight do not have to be at the same distance from the pulley to balance.

Picture a similar situation but with the monkey and weight on ice (i.e. frictionless) and the pulley horizontal not vertical. This is more real life and easier to see (They do have some ice rinks in land of smog - right?). As the monkey pulls, both the monkey and the weight will move equal amounts toward the pulley.

I'm a little rusty in physics and I can't remember why the rope had to be weightless but I like your example of the ice (BTW, yes, we have 4 ice rinks in this polluted place, and I worked last month with Holiday on Ice and they gave me a chance to use their rink once, hehe).
Only question I have, in that theorical situation, Why would it be possible for the weights to be at different heights? I can understand it perfectly on the ice, but in a vertical situation I lost the subtleness of the theory. Has to do with the frictionlessnes?

Beachwolverine · 08-10-2004

Jesus,

My humble opinion. If you have two equal weights (forget the monkey) tied to the ends of a real (i.e. with weight) rope and hang them over a frictionless pulley, they will be in equilibrium ONLY at equal height. This is because the weight of the rope is also acted upon by gravity, so on each side you have the weight of the rope+weight and they must be at equal height to balance. If you pull down on the left side and hold, you now have more weight on the left due to more rope and when you let go, the left side will fall.

I think the comprehension problem come from the fact that we find it hard to picture a weightless rope. But if there is a weightless rope and the weights are at different heights, they would still be balanced with the same weight pulling down on both sides. This seems odd, but I can think of no reason why this wouldn't occur - gravity acts on both weights equally and with no other weight, they should not have to be equal distance. With a weightless rope if you pull down on the left side, hold, then release, you still have equal forces on both sides and the weights will not move - at least that is my belief.

BW

rick muldoon · 08-15-2004

Hey Bumper
Did you walk or take a lunch to school??

Sue · 08-15-2004

Quote:

Originally Posted by rick muldoon

Hey Bumper
Did you walk or take a lunch to school??

Where did that come from? Years and years ago, a high school friend looked across the table at me and said, "Do you walk to school or carry your lunch?" as if it just came into her head. And we laughed and laughed and laughed.

**Bumper** · 08-15-2004

Quote:

Originally Posted by rick muldoon

Hey Bumper
Did you walk or take a lunch to school??

The elusive, legendary Rick Muldoon!! As I live and breathe!! Did you finally fool the parole board, get one past the insanity review panel in the looney bin, or what? When you didn't show up at the appointed rendezvous last February, after expressing such enthusiasm, and I hadn't seen a post from you since, I figured you were mad at us, or you had come to your senses, or something. Anyway, welcome. As for your question, I walked to school, but once there, I "took" lunches. I think that may have been the start of my weight problem. (I don't think I know of anyone who took a lunch to school. I did, however, know lots of people who took a bus to school. Ba-Dum-Bum!)

**Jesus** · 08-16-2004

Quote:

Originally Posted by Beachwolverine

.... But if there is a weightless rope and the weights are at different heights, they would still be balanced with the same weight pulling down on both sides.

Thanks a lot, I knew the weightless rope had some extrange role, but couldn't remember why.

qed.

08-15-2004	#36 (permalink)
rick muldoon into ruins Join Date: Jan 2004 Location: windsor ont Posts: 70	ouch Hey Bumper Did you walk or take a lunch to school??

08-10-2004	#35 (permalink)
Beachwolverine life=playa Join Date: Sep 2003 Posts: 615	Jesus, My humble opinion. If you have two equal weights (forget the monkey) tied to the ends of a real (i.e. with weight) rope and hang them over a frictionless pulley, they will be in equilibrium ONLY at equal height. This is because the weight of the rope is also acted upon by gravity, so on each side you have the weight of the rope+weight and they must be at equal height to balance. If you pull down on the left side and hold, you now have more weight on the left due to more rope and when you let go, the left side will fall. I think the comprehension problem come from the fact that we find it hard to picture a weightless rope. But if there is a weightless rope and the weights are at different heights, they would still be balanced with the same weight pulling down on both sides. This seems odd, but I can think of no reason why this wouldn't occur - gravity acts on both weights equally and with no other weight, they should not have to be equal distance. With a weightless rope if you pull down on the left side, hold, then release, you still have equal forces on both sides and the weights will not move - at least that is my belief. BW

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