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55 50 Ron · Jan 27, 2011

Had a chance to help a grand daughter with homework.

5th grade science and the book was describing levers with first class, second class and third class levers. I've never heard of "classes" of levers. I told her to tell her teacher that grandpa didn't agree with the book's description. LOL.

Some drawings didn't make sense, at least common sense!!

Can anyone "shed some light" on this?

DeltaRed · Jan 27, 2011

I've heard of simple and compound levers-dont really remember the difference.never heard of "classes" of levers.When you find out,please let us know.Thanks.

NW Ohio Tim · Jan 27, 2011

This is pretty good......

Tim

larry@stinescorner · Jan 27, 2011

Iguess were all not smarter than a fifth grader! lol

willie in mn · Jan 27, 2011

Bingo, you got it, Tim. Give the man a seegar, or a kewpie doll for his SWMBO.
Willie

Spook · Jan 27, 2011

I had that in middle school. Maybe I was a little slow.....

Geo-TH,In · Jan 27, 2011

Isn't there a TV show about being smarter than a 5th grader?

Nebraska Cowman · Jan 27, 2011

That's interesting. The chunk of wood we used for the fulcrum dad always called "bait"

Anonymous-0 · Jan 27, 2011

First class levers=pry bar=work
Second class levers=wheelbarrow=work
Third class levers=fishing pole=fun!
Got it!

Dave Sherburne NY · Jan 27, 2011

When I went to school 55 yrs ago we only had 1 kind of lever, and if it was put together right and long enough it would move the earth. I've no use for the wheel barrow lever but the fishpole lever I'm willing to try.

IBorange in TX · Jan 27, 2011

Man uses some simple machines to make work easier. There are 6 simple machines and levers being one of the six. Levers are divided into 3 different classes according to the location of the fulcrum in relation to the weight and effort force. Using levers, man is able to gain speed, change in direction, or effort. Of course, man is more interested in gaining effort. In other words, move more weight with less effort. In the first class lever, change in direction is gained,but also effort or speed can be gained depending on the location of the fulcrum. In fact, a simple pulley acts as a lever, gaining only change of direction. You pull down, the object goes up. In the second class lever,change of direction, nor speed can be gained,but only effort is gained again according to the location of the fulcrum. The third class the only thing gained is speed.
I know,its clear as mud, but you asked. How do I know, taught Physics for 35yrs.
God Bless,

Pops1532 · Jan 27, 2011

The book is right. I suspect Grandpa shouldn't be helping with science or math homework. Social studies, spelling, grammar, and history are probably a different story.

OldFarmTractor · Jan 27, 2011

Levers are Easy.. As easy as 1... 2... 3
When you consider what is in the center
it's F...R...E

old · Jan 27, 2011

Sounds like another way to make something that should be simple into a computer needed thing to figure out. Now days they make stuff so hard it is not wonder few people have much if any common sense. Why not just keep it as Atlas said. Give me a long enough lever and I will move the world

55 50 Ron · Jan 27, 2011

NW Ohio Tim. Interesting sketches you provided. They just added to my LOL condition because in the grand daughter's "science" book it showed the hammer pulling a nail as "second class" lever but the sketch you showed says hammer pulling nail is "first class" lever. I'm a retired engineer and I too studied physics. I still think there is some "magic" going on here!!

55 50 Ron · Jan 27, 2011

I just took a closer look at the "first class" drawing that Tim posted. Look closely at the "E" force. When you pull up as the "E" shows it just lifts the bar (lever) off the fulcrum. The nail doesn't move at all. Hokey Pokey for sure. Common sense is out the window on that drawing!!

Ken Macfarlane · Jan 27, 2011

Have a mechanical engineering degree, took all kinds of physics,
kinematics and dynamics, statics, etc. dealing with all kinds of lever
type analysis.

Not once did "class" of lever ever come up, have never even heard
of the idea of classifying them. Why would anyone even bother? Its
not used in engineering.

camju · Jan 27, 2011

you got it all wrong,LOL. the E is efort on the hammer is up not down.BUT that said class 1 has the pivot(fulcrum) point in the center class 2 on the end and E(efort) on the other end.class 3 has Folcrum on the end and E on the middle.That is the diffrence between class1,2,3.

55 50 Ron · Jan 27, 2011

You're exactly right. The "E" effort IS UP on the drawing for the hammer for first class and that won't do a thing to the nail. Look at what Mr. McFarlane wrote below. I agree with him 100%.

55 50 Ron · Jan 27, 2011

In the drawing for the hammer, the "E" force must point down NOT UP to do any good.

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