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M o d e l N o . M E - 9 5 0 2 E x p . 1 2 : S i m p l e M a c h i n e s – T h e L e v e r
0 1 2 - 1 2 8 7 6 B 73
Exp. 12: Simple Machines–The Lever
Equipment Needed
Theory
The workings of a lever can be understood using the
concept of torque. When the torque produced by the
applied force (called the “effort”) becomes greater than
the torque of the object being lifted (called the “load”),
the lever will rotate about its pivot point (sometimes
called the “fulcrum”), raising the load. However, levers
can also be explained in terms of work and the conser-
vation of energy.
In physics, the precise mathematical definition of work is the force applied to an object multiplied by the distance
over when that force acts, or
W = Fd where W is the work, F is the applied force, and d is the displacement of the
object in the direction of the force. (If a force is applied to an object, but the object does not move in the direction
of the force, then, technically, no work is done.) Whenever work is done on an isolated system, the energy of the
system will change by exactly the amount of work that was performed, or

E = W where

E is the change of
energy.
In this experiment, you will apply a measurable amount of work to a lever and observe the change in the gravita-
tional potential energy of the load.
Setup
1. Put a Protractor at each end of the Balance Arm beam and mount the Balance Arm on the Statics Board with
the beam centered in the pivot.
Item Item
Statics Board Mounted Spring Scale
Mass and Hanger Set Balance Arm and Protractors
Large Pulley Thread
Pencil or Dry Erase Marker Pen
Figure 12.1: Lever
Figure 12.2: Equipment Setup
Spring
Scale
Pivot
Balance
Arm
Protractor
Protractor
Large
Pulley
Hanging
Mass
Thread
M
1