Maths question.

[MajorProblem]

If I can lift a bar which weighs 552lb and is 5 yards long by picking it up from floor level to waist height at one end only can anyone tell me how much weight I've lifted?

[Ved]

Depends on the angle at finish. Look up angular kinetics. It's similar to the force requires to turning a nut with a short and long spanner.

Enjoy. Sleep well.

[Harpo]

552 Lb. Hth.

A ton of feathers is less though shirly ............ sometimes.

[Alfanatic]

My rough, old, unexercised and out of date maths schooling tells me this is a question about torque.

The bar, if uniform, weighs an equivalent of 552lb at its mid point. The end that stays on the ground becomes the centre around which the torque acts. Torque is perpendicular force * distance from the centre. If you lift at the other end (not the one that will remain on the ground), you double the distance therefore halve the force, so you have exerted whatever force is equivalent to half of 552lb (i.e. 276 lb) to lift that end of the bar. As the angle of the bar changes, the force due to gravity produced by the weight of the bar moves away from perpendicular. Thus the perpendicular component that you are trying to overcome reduces as the bar rotates towards vertical. The highest the force gets, then, is when you initially lift one end from the ground, and that will be equivalent to lifting 276lb. If you try to lift the bar at its midpoint instead of at one end, even just to lift one end off the ground, you will need to muster the full 552lbs worth of effort.

Maybe

Edited by Alfanatic on Tuesday 3rd December 20:35

[kambites]

Half the weight as it first leaves the ground diminishing as the angle of the bar increases.

So roughly 1161 Newtons, initially if you're at sea level.

Edited by kambites on Tuesday 3rd December 20:38

[mybrainhurts]

I can see you ain't fecked your rotator cuff, have you...?

[balls-out]

kambites said:

Half the weight as it first leaves the ground diminishing as the angle of the bar increases.

So roughly 1161 Newtons, initially if you're at sea level.

Edited by kambites on Tuesday 3rd December 20:38

A Newton is a measure of force, not weight.

[iloveboost]

LOL at this thread.
I have a question. Two cars are travelling at 50mph one is in a vacuum one isn't which one travels further in exactly one hour?! I think it's something to do with drag.
So many wind up threads on here of late it's genuinely hard to know sometimes if people are being a bit thick or actually haven't got a clue. This is what you would call a rhetorical question as it implies an answer is needed when it's in the dam question!

Edited by iloveboost on Tuesday 3rd December 21:07

[Squiggs]

More than a packet of crisps, less than an elephant. HTH

[Alfanatic]

Weight is a force, mass times gravity, and is measured in newtons.

For the purpose of the question, answering in equivalent mass (lbs) would, I'd have thought, make more sense to the OP than answering in newtons. Kambites was kind enough to provide both.

[kambites]

balls-out said:

A Newton is a measure of force, not weight.

Weight is a force.

If the OP actually wanted the equivalent mass, I'd sort of assumed he could divide by two himself.

If he wanted the actual mass he'd lifted, the answer is of course 522lbs but on average he'd lifted it by half the height that he'd lifted the end of the bar by (if that makes sense).

Edited by kambites on Tuesday 3rd December 21:06

[Alfanatic]

iloveboost said:

LOL at this thread.
I have a question. Two cars are travelling at 50mph one is in a vacuum one isn't which one travels further in exactly one hour?! I think it's something to do with drag.
So many wind up threads on here of late it's genuinely hard to know sometimes if people are being a bit thick or actually haven't got a clue.

Being cars, vacuum or not it seems reasonable to assume they are on a road. In which case the one travelling in air travels further. The engine in the car in the vacuum stops due to lack of oxygen and the rolling resistance of the wheels and drivetrain slow the car down.

[iloveboost]

Alfanatic said:

Being cars, vacuum or not it seems reasonable to assume they are on a road. In which case the one travelling in air travels further. The engine in the car in the vacuum stops due to lack of oxygen and the rolling resistance of the wheels and drivetrain slow the car down.

Hehe I like that you picked up that it was a double trap.

[balls-out]

kambites said:

balls-out said:

A Newton is a measure of force, not weight.

Weight is a force.

If the OP actually wanted the equivalent mass, I'd sort of assumed he could divide by two himself.

If he wanted the actual mass he'd lifted, the answer is of course 522lbs but on average he'd lifted it by half the height that he'd lifted the end of the bar by (if that makes sense).

Edited by kambites on Tuesday 3rd December 21:06

I hate it when I'm wrong

[stuartmmcfc]

Alfanatic said:

Being cars, vacuum or not it seems reasonable to assume they are on a road. In which case the one travelling in air travels further. The engine in the car in the vacuum stops due to lack of oxygen and the rolling resistance of the wheels and drivetrain slow the car down.

I misread the original question as being about cats
I hadn't got a fking clue tbh

[Alfanatic]

iloveboost said:

Hehe I like that you picked up that it was a double trap.

I thought you were going to say the driver kicked the rear window out and the escaping air pushed the car up to 88mph and it arrived before it left, or something