Balance and Equal Gears
project 2 of 4
The following lesson is part of a series that should be explored in a sequential manner. Students will need the full exploration each concept in order to move from one phase of Levers, Arms and Fulcrum Points to the next. It is more than just play at this level. The purpose of these exercises is to take the concept of play into the field of science. It may not be easy, but it’s certainly will be fun!
New Understanding of Mechanical Advantage
This project plan will introduce the concept of force and distance trade-offs in levers and how the same principles relate directly to gears. Students will eventually be able to explore different ratio relationships as they move to experiment with the different sized gears and calculate the mechanical advantage of a simple machine. This project plan starts that journey by examining the mechanics of gears of equal sizes. Students should not start this lesson until they have experienced the building of horizontal and vertical planes on which the gears can be mounted.
Challenges for Students
This exercise will enable students to see the relationship of how beams balance on a fulcrum and how equal size gears move at the same speed.
Begin by breaking up the class into groups with 3-4 students in each. Then ask students to build a fulcrum point and balance a long plank i.e. something resembling a seesaw. This may look different amongst the various groups. Remind your students that the goal is to balance without making things overly complicated.
Ask students to draw the lever arm on the face of the gears with dry-erase markers. This extends from the center of the gear out to the teeth. As the gears of equal size rotate, students will see how gears with equal size have lever arms of equal length and move at the same speed. This can be compared to how either end of a balanced beam moves up or down at the same rate.
HINT: In the example of the gears, the fulcrum is the axle which is located in the center of the gear that holds the gear in place. The size of the gear determines the length of the lever arm.
As students play with balancing the long plank, ask them to build a simple vertical plane where gears of equal size are able to move freely. Have students choose two gears that can rotate at the same speed with the same strength.
HINT: As students are working ask them to talk about what they are noticing about the rate of the gears moving and ask them to compare it to the way in which the balance beam moves up and down and then can rest balanced in the middle.