Lever Tasks

[prelude to death]

First of all, I know that this isn't the place for official clarifications, but I was wondering what you guys think about the following: Say I had a 1st class lever (sort of like a seesaw), and when I dropped the effort onto the seesaw, the load rises. The load is attached to a 2nd class lever (sort of like a wheelbarrow) by a string. The load then turns into the effort, and the ball - or the load, in this case - would fall out and hit another object, continuing the device. I was just wondering if I made sure the IMA is greater than 5, would that be able to qualify for Task 4f? The only reason I'm not sure is that I'm not sure if that 'utilizes the IMA greater than 5 to cause the next action' or not.

Thanks in advance!

The big question is if the input 'effort' on the 1st class lever were applied directly to the string ('effort') of the 2nd class lever, would the final ball or load still be moved? If it would, you wouldn't be utilizing an IMA greater than 5.

Okay, thanks a lot! Also, how would you find the IMA of a compound lever? I know how to find the IMA of each lever, so if, say, I put two levers together, and each had an IMA of 2, would I just add the two IMAs together to get a final IMA of 4 for the compound lever?

[chalker]

Also, how would you find the IMA of a compound lever? I know how to find the IMA of each lever, so if, say, I put two levers together, and each had an IMA of 2, would I just add the two IMAs together to get a final IMA of 4 for the compound lever?

The link I gave above helps explain how to calculate IMA for compound levers: http://en.wikipedia.org/wiki/Compound_lever

[Science-dad]

Hi guys,

Hope you can stand one more question on this. I'm just a parent and still confused. If we use a class 1 lever which is pushed down by a mass and the other end of the lever pushes up on a wheel barrow style lever (class 1 or 2 not sure) and the mass that is on that lever as it rises causes the next event, is that combined?

Thanks

[chalker]

Hi guys,

Hope you can stand one more question on this. I'm just a parent and still confused. If we use a class 1 lever which is pushed down by a mass and the other end of the lever pushes up on a wheel barrow style lever (class 1 or 2 not sure) and the mass that is on that lever as it rises causes the next event, is that combined?

Thanks

Yes

[Science-dad]

Hi guys,

Hope you can stand one more question on this. I'm just a parent and still confused. If we use a class 1 lever which is pushed down by a mass and the other end of the lever pushes up on a wheel barrow style lever (class 1 or 2 not sure) and the mass that is on that lever as it rises causes the next event, is that combined?

Thanks

Yes

Thanks so much for the help. You and your brother have been lifesavers.

[mattravn]

So I couldn't find this one while look about in the discussions so far. Sorry if this one is already out there.

For IMA - If the calcuation is the ratio of force out / force in (i.e. you can use a lever with an IMA of 2 to pick up a heavier object with a lighter one), then what about third class levers? Is the IMA of a third class lever < 1 since your output force is going to be lower (albiet faster)?

Thanks. We are pondering the compound lever question, but I think since we are shooting for IMA of 5 it makes more sence to do a first and second class levers so they work together.

Later.

[mnstrviola]

I don't believe third degree levers have IMA. They actually require more work to lift a load no matter how you set them up.

[fleet130]

You're on the right track, with one slight mistake.

IMA is what the mechanical advantage would be in a "perfect" system ignoring friction. It is calculated using length/distances or velocities (velocity =distance/time))

IMA = Distance traveled by the Effort / Distance traveled by the Load
or
IMA = Length of the Effort Arm / Length of the Load Arm
or
IMA = Velocity of the Effort / Velocity of the Load

AMA is the actual Mechanical Advantage produced by the machine. It is calculated using forces.

AMA = Force of the Load / Force of the Effort

Note the Effort figure is in the numerator for IMA and the denominator for AMA.

In a 1st Class Lever, the Effort Arm can be greater than, shorter than, or the same length as the Load Arm, so the IMA can be greater than, less than or equal to 1.

Since the Load Arm of a 2nd Class Lever is always shorter than its Effort Arm, the IMA is always greater than 1.

The Effort Arm of a 3rd Class Lever is always shorter than the load Arm, so the IMA is always less than 1.

These relationships could also be defined using AMA and the Effort/Load Forces.

Edit:

I don't believe third degree levers have IMA. They actually require more work to lift a load no matter how you set them up.

But they do provide an advantage if your goal is to increase the velocity or distance between effort and load. The price to pay is it takes more effort (force).

[mnstrviola]

You're on the right track, with one slight mistake.

IMA is what the mechanical advantage would be in a "perfect" system ignoring friction. It is calculated using length/distances or velocities (velocity =distance/time))

IMA = Distance traveled by the Effort / Distance traveled by the Load
or
IMA = Length of the Effort Arm / Length of the Load Arm
or
IMA = Velocity of the Effort / Velocity of the Load

AMA is the actual Mechanical Advantage produced by the machine. It is calculated using forces.

AMA = Force of the Load / Force of the Effort

Note the Effort figure is in the numerator for IMA and the denominator for AMA.

In a 1st Class Lever, the Effort Arm can be greater than, shorter than, or the same length as the Load Arm, so the IMA can be greater than, less than or equal to 1.

Since the Load Arm of a 2nd Class Lever is always shorter than its Effort Arm, the IMA is always greater than 1.

The Effort Arm of a 3rd Class Lever is always shorter than the load Arm, so the IMA is always less than 1.

These relationships could also be defined using AMA and the Effort/Load Forces.

Edit:

I don't believe third degree levers have IMA. They actually require more work to lift a load no matter how you set them up.

But they do provide an advantage if your goal is to increase the velocity or distance between effort and load. The price to pay is it takes more effort (force).

Thank you fleet

Is anyone doing the third degree lever task? If so, how are you doing it?

[mattravn]

You're on the right track, with one slight mistake.

IMA is what the mechanical advantage would be in a "perfect" system ignoring friction. It is calculated using length/distances or velocities (velocity =distance/time))

IMA = Distance traveled by the Effort / Distance traveled by the Load
or
IMA = Length of the Effort Arm / Length of the Load Arm
or
IMA = Velocity of the Effort / Velocity of the Load

AMA is the actual Mechanical Advantage produced by the machine. It is calculated using forces.

AMA = Force of the Load / Force of the Effort

Note the Effort figure is in the numerator for IMA and the denominator for AMA.

In a 1st Class Lever, the Effort Arm can be greater than, shorter than, or the same length as the Load Arm, so the IMA can be greater than, less than or equal to 1.

Since the Load Arm of a 2nd Class Lever is always shorter than its Effort Arm, the IMA is always greater than 1.

The Effort Arm of a 3rd Class Lever is always shorter than the load Arm, so the IMA is always less than 1.

These relationships could also be defined using AMA and the Effort/Load Forces.

Edit:

I don't believe third degree levers have IMA. They actually require more work to lift a load no matter how you set them up.

But they do provide an advantage if your goal is to increase the velocity or distance between effort and load. The price to pay is it takes more effort (force).

Thank you fleet

Is anyone doing the third degree lever task? If so, how are you doing it?

Thanks guys, that is what I thought on the third class lever (fetchez la vache). I am probably not doing the third class lever, but I had thought about setting up a third class lever which would move in an arc parallel to the floor (i.e. sweep past) with a hopper to pick up an object which it could bash into or roll onto a ramp to continue. The parallel to the floor seemed to be safer than trying to catapult it across the box. Best of luck if you try for it.