Lever
In physics a lever is a rigid object that is
used with an appropriate fulcrum or pivot point to multiply the mechanical force
(effort) that can be applied to another object (load). Lever is one of the six
simple mechanics. Products such as lever support, lever clamp and lever
stick are used to teach, learn and demonstrate the
fundamental concepts of lever, moments, and mechanical advantage.
For demonstration of levers and
related experiments or calculations, the lever clamps are mounted on two
opposite ends of the lever stick and the location of fulcrum or pivot
point is changed until a balance is reached. |
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Lever Clamp (Knife Edge Clamp)
Lever clamp is a dual function device that can be used
as a pivot point and to hang the load and effort forces. Lever clamp has
an opening for inserting the lever stick. Lever stick can easily slide
into the opening and it can be secured at any location using a thumb
screw on the top of the lever clamp. Each lever clamp has two side arms
used as pivot point to hold the lever on any standard lever stand or
lever support. The same arms can also support a wire hanger used to hang
the load or effort forces. The wire hanger can be removed for when you
use the lever clamp as pivot point. |
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Lever Stick
Lever stick is a long wooden stick
made of hardwood and is graduated in millimeters, centimeters and
decimeters. Lever stick is 25 mm wide and 5mm thick. Lever sticks
are available in 50 cm and 100 cm lengths. |
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Lever Support (Lever Stand)
Lever
supports are are available in two different types. Either one is good
for all lever related experiments; however, the cast metal lever support
is taller.
Cast Lever Support
The cast lever support stands 18.5 cm
tall. Made of aluminum alloy, it has a small foot print and a single
piece structure that contributes to its durability.
The base is about 7 cm x 8 cm.
There are two groves on the top for
supporting knife-edge lever clamp.
It weighs 220 grams. |
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Traditional Lever
Support
The traditional lever support stands 13 cm
tall. It has a heavy cast iron base with nickel plated steel columns.
The base is about 9 centimeter in
diameter.
It weighs about 450 grams.
How to select a
lever support?
Choice are a heavy short fulcrum or a
light tall fulcrum. The wire hangers on a lever clamp plus a tall weight
with hook require about 14 cm space. So 13 cm height will not be enough.
The shot/ heavy lever stand is only recommended when you are using short
weights or you are hanging the weights directly to the lever stick.
Otherwise the taller lever stand is a safer choice. |
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Weights with Hooks
Weights with hooks such as weight
hangers with slotted masses may be used as the load in lever related
experiments. Such weights may be hanged to the lever clamp or to the
lever sticks. |
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Spring Scales
Spring scales may be used as the
effort. Spring scales can easily show how much force is used as the
effort to balance the load.
Spring scales are often graduated in grams and in Newtons. Select the
capacity of the spring scale the same as the load you are using for your
experiments. For example use a 500-gram spring scale when experimenting
with a 500-gram load. |
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Spring scales
are sold separately, but you can make more accurate measurements if you have a
complete set.
Lever Demonstration
Set A lever demonstration set
includes all you need to assemble a basic lever for demonstration. You
will also need weights with hooks, weight hangers with slotted weights
or spring scales to complete your demonstration or experiments. This set
includes a lever support, 3 lever clamps and one lever stick or meter
stick.
While ordering you will get the choice
of 100 centimeter stick or 50 cm stick.
Lever demonstration set may be used to
show the principles of levers, torque or moment and mechanical
advantage. |
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The image on the left shows how a
lever set along with a 100-gram weight and a 500-gram weight are used to
demonstrate the action of a lever system. The 100-gram weight is fully
in balance with the 500-gram weight. |
This is another creative idea using a lever
demonstration set. By hanging two lids from metal cans this set is converted to
a balance scale.
Balance scales and levers are very
similar. As a matter of fact many balance scales known as bench scales
or platform scales use the lever system for measuring heavy weights.
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Teaching the mechanics
of Levers.
Start by talking about what a lever
does in order to create some interest and excitement about the subject.
Tell them that they can easily lift a car alone with the help of levers.
Or they can lift their friend with the push of one finger.
Then explain the parts of a lever such
as Fulcrum and a long solid object. In the classroom you will use a
lever support as a fulcrum and a lever stick as the solid object. If you
wanted to show more practical applications or lifting a person with one
finger, then you can by a 6 feet long 2 x 4 pine wood and a of break.
The advantage of using a lever stick is the ability to read distances
and calculate the torque and mechanical advantage. |
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Torque is the force that causes an item to
rotate. Torque is calculated in "Newton meter" or "pound-feet".
To calculate the torque or moment, multiply the force by its distance from the
fulcrum.
The mechanical advantage (MA) of a lever is the
factor by which a lever multiplies the force put into it. For example if you use
1 Lb force to lift a 15 Lb object, then the mechanical advantage will be 15.
Distributors of scientific and educational products
Where to buy?
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