Rube Goldeberg Edition
Brown, Duong, Menth, Keeler
Simple Machines
Levers
There are three different types of levers: first class, second class, and third class. All levers have an imput force (effort), an output force (load) and a fulcrum. Dividing the output force by the input force on a simple machine is how to find the mechanical advantage of that specific machine. The formula specific to finding the mechanical advantage of levers is the input arm divided by the output arm. The input arm is the length between the fulcrum and the input force, while the output arm is the length between the fulcrum and the output force.
First Class Lever
First class levers are defined by their fulcrum, which is in the middle. On either side of the fulcrum there is the input force (effort) and the output force (load). Some examples of a first class lever are see saws, catapults, and even your arm.
A first class lever is present in our machine and it is used to release a toy car.
Input Force Output Force
Second Class Lever
A second class lever can be differentiated from a first class lever by the position of the fulcrum, input force, and output force. The fulcrum is on one side of the lever and the output force is in the middle, between the fulcrum and input force. On the lever, the input force is located on the opposite end of the fulcrum. Examples of the second class lever include wheel-barrows, staplers, and wagons.
There is no second class lever displayed in our Rube Goldberg Machine.
Output Force
Input Force
Third Class Lever
The third class lever is similar to the second class lever. The fulcrum is always on the opposite end of the output force. The input force is between the fulcrum and the output force. Some examples of this type of lever would be a fishing pole, a hammer, and a base ball bat.
A third class lever is not included in our machine.
Input Force
Output Force
The image on the left is our homemade first class lever. The tennis ball shown falls off of a platform and onto the lever. The ball gains kinetic energy as it falls and it becomes the input force for our lever. As shown in the photo, the lever has the fulcrum in the middle with the input force on one side and the output force on the other. The output force for this lever unhooks a bolt that is keeping Lightning McQueen from rolling forward.