Mechanical advantage. Let's examine how to apply lever ratios to calculate the
mechanical advantage. In basic mechanisms every time you open a door you are using
a class-2 lever to multiply force. this multiplication of force is called
mechanical advantage. the formula used to calculate mechanical advantage is f2 the
output force divided by f1 the input force. The Nutcracker is another example
of using a class-2 lever to multiply force. you can calculate this
multiplication of force by substituting the values of f1 and f2 into the
mechanical advantage formula. but before doing this you must determine the values
of f1 and f2 using the lever ratios. where f1 equals input force, f2 equals
output force. L1 equals input length L2 equals output length. s1 equals input
displacement and s2 equals output displacement. mechanical advantage or ma,
equals f2 over F 1. Given L1 equals 4.5 inches, L2 equals 1.5 inches, and f1
equals 5 pounds ,we calculate f2 by cross-multiplying. in this example f2
equals 15 pounds you can now calculate mechanical advantage by dividing f2 by
f1 15 pounds divided by 5 pounds equals 3
in this example a class 2 lever was used to multiply the 5 pound input force by 3
to exert a 15 pound force on the nuts or output force here the mechanical
advantage equals 3 let's do a quick review before we move on
mechanical advantage equals F 2 divided by F 1 which equals the output force
divided by the input force in this example appliers
which is a class 1 lever is used to multiply force the procedure to
calculate mechanical advantage in a class 1 lever is the same as shown
previously with the class 2 lever given the information above use the lever
ratios and the mechanical advantage formula to calculate mechanical
advantage given L 1 equals 5 inches L 2 equals 2 inches in F 2 equals 50 pounds
we calculate F 1 by cross-multiplying here F 1 equals 20 pounds the mechanical
advantage equals F 2 divided by F 1 so here the mechanical advantage is 50
pounds divided by 20 pounds so the mechanical advantage equals 2.5
applying lever calculations to rotational devices besides making it
easier to grip the handle on a screwdriver also multiplies the force
exerted when turning a screw the picture to the left shows the inside of a drill
that is being used as a powered screwdriver. the shaft inside the
screwdriver serves the same purpose as the handle on the manual screwdriver. the
fulcrum of the lever is centered on the handle on the shaft and on the flat head
screwdriver piece. if the force exerted by the shaft is 15 pounds calculate the
force at the tip of the screwdriver and the mechanical advantage. we know f1
equals 15 pounds L1 equals 0.3 1 to 5 inches and L2 equals 0.09375 inches.
We can calculate f2 by cross-multiplying. the mechanical
advantage equals 50 pounds divided by 15 pounds. So here the mechanical advantage
is 3.3. Congratulations, you have completed this learning activity on
mechanical advantage.