Machines B/C

[InsertNameHere123]

Hey, so when the examiners weigh the masses before hand, does anyone know if they include the weight of the hook in their calculations for ratio? It's especially skewing in instances where the objects are really light, and I'm just worried that we're going to get skewed if the hook for the practical isn't included. Thanks in advance!

Because you are trying to find the ratio of two masses and not the actual masses of the two objects, I don't think the weight of the hook matters as long as they are the same for each of the weights.

But like, lets say object A was 20 and B was 30. The hookk weighed 6. While the objects ratio would be 2:3 with the hook it would be 13:18 which skews the results relatively significantly. So, I believe it does impact it but not sure...

[Umaroth]

Hey, so when the examiners weigh the masses before hand, does anyone know if they include the weight of the hook in their calculations for ratio? It's especially skewing in instances where the objects are really light, and I'm just worried that we're going to get skewed if the hook for the practical isn't included. Thanks in advance!

Because you are trying to find the ratio of two masses and not the actual masses of the two objects, I don't think the weight of the hook matters as long as they are the same for each of the weights.

But like, lets say object A was 20 and B was 30. The hookk weighed 6. While the objects ratio would be 2:3 with the hook it would be 13:18 which skews the results relatively significantly. So, I believe it does impact it but not sure...

They do not provide hooks, only loops of string from which you can hang the masses. If you are going to use hooks, you have to use your own.

[AlfWeg]

Because you are trying to find the ratio of two masses and not the actual masses of the two objects, I don't think the weight of the hook matters as long as they are the same for each of the weights.

But like, lets say object A was 20 and B was 30. The hookk weighed 6. While the objects ratio would be 2:3 with the hook it would be 13:18 which skews the results relatively significantly. So, I believe it does impact it but not sure...

They do not provide hooks, only loops of string from which you can hang the masses. If you are going to use hooks, you have to use your own.

and make them as lightweight as possible.....

[JoeyC]

So in order to attach the weights to my device, I plan on using rubber bands, running the loops of string through them or using them as friction devices. Basically the rubber bands will serve as the lightweight adjustable hooks in their role of securing weights on the lever device in a manner that can be adjusted.
This is allowed by the rules, correct?

[Creationist127]

So in order to attach the weights to my device, I plan on using rubber bands, running the loops of string through them or using them as friction devices. Basically the rubber bands will serve as the lightweight adjustable hooks in their role of securing weights on the lever device in a manner that can be adjusted.
This is allowed by the rules, correct?

I think so. The only things listed as prohibited are electronics, springs, and masses, other than a fixed counterweight.

Speaking of fixed counterweights, my machine has a problem where I need to adjust the counterweight every run to maintain balance. What causes this?

[JoeyC]

What’s your machine made of? (Need more specifically to diagnose)

Another question:
Picture a first class lever (seesaw type). Now keep that image the same but move the effort into between the load and fulcrum. It counts as a second class lever even though the design is still the seesaw design because of the way the effort and load and fulcrum are ordered, correct?

[jaggie34]

What’s your machine made of? (Need more specifically to diagnose)

Another question:
Picture a first class lever (seesaw type). Now keep that image the same but move the effort into between the load and fulcrum. It counts as a second class lever even though the design is still the seesaw design because of the way the effort and load and fulcrum are ordered, correct?

Ours is mostly wood, and that would count as a third class lever since the effort is between the fulcrum and resistance

[Creationist127]

What’s your machine made of? (Need more specifically to diagnose)

Another question:
Picture a first class lever (seesaw type). Now keep that image the same but move the effort into between the load and fulcrum. It counts as a second class lever even though the design is still the seesaw design because of the way the effort and load and fulcrum are ordered, correct?

Ours is mostly wood, and that would count as a third class lever since the effort is between the fulcrum and resistance

Yes, that would be 3rd class—all that matters is the effort and load, not the design.
Mine is made of wood, attached to ball bearings, attached to screws. I don’t really understand what would make the centers of mass move, since its mass isn’t changing between runs.

[JoeyC]

Probably something to do with how the wood or ball bearings sit on the nail (which I assume is the axis/fulcrum). Remember that center of mass isn't determined just by mass, but also by distribution of it. If the ball bearings or something on the lever ends up in a different position than how it began - when it was in perfect balance - then that center is going to shift. I suspect that maybe the ball bearings have too much space in between them so that when one moves there's a significant offset in mass at that position (as compared to little space in between them where if one moved in that same space there would likely be another ball there at that position)

[EastEagle991]

Does anybody have pictures of levers from past years? I'd like to see some ideas.