COMPOUND MACHINES
Define the Problem
Generate Concepts
Develop a Solution
Construct and Test Prototype
Our team decided to build the design including the simple machines inclined plane, wheel and axle, and a pulley system. The book will be pulled up an inclined plane by a double pulley system, powered by a wheel. By using a human force to turn the wheel and axle the gears will turn. These gears then turn the pulleys and the strings pull the book try up the inclined plane. The book will land on the shelf which is 12.75 inches above the surface which solves the problem statement of lifting a book 12 inches.
IMA of 1st machine (inclined plane) = 1.951
IMA of 2nd machine (wheel & axle) = .66
IMA of 3rd machine ( pulley) = 2
TOTAL IMA = 2.44
IMA of 2nd machine (wheel & axle) = .66
IMA of 3rd machine ( pulley) = 2
TOTAL IMA = 2.44
Evaluate Solution
This project of creating our compound machine was very rewarding, but at times stressful. Our team did successfully create a functioning compound machine that completed our task of moving a textbook 12 inches. However, we did face many challenges along the way. We struggled greatly with time management and, using the new VEX materials efficiently. Although we were stressed our team worked well together and used each other as resources to bounce ideas off one another. After many set backs we finally created a functioning machine and was able to test it to see if it would work. We had to apply a lot of force to the wheel to pull the book up the plane with the pulley, but after many attempts we were successful! The machine had an IMA greater than 1 therefore, it was efficient in its task. If we were to redo our project and process I would definitely try to combine all of our ideas and have a definite solution before we began building. I would also try to decrease the amount of resistance force (tray) working against the effort force. Our team wasted a lot of time not knowing what to do and having to make decisions through trial and error. However, this did help us to work more cohesively together trying to find a successful solution. Also, I learned how to think of my feet quickly, needing a solution to a problem instantly. Finally, in order to create a efficient machine we had to change the skinny track to two rails. This was easier for the tray to glide up because it did not have screw heads interfering. Also, we had to change our pulley system, using the ones that connect to gears, in order to have more power against the resistance.
Conclusion
- The pulley system was the easiest mechanism to calculate out of all simple machines. This is because the IMA is the number of strings going against the resistance force, in our machine it was 2.
- The wheel and axle was the most difficult to calculate the mechanical advantage because the IMA is the effort diameter (wheel) divided by the resistance diameter (axle), having such small material that difficult to correctly measure our made finding our dimensions very tricky.
- In order to make our compound machine more efficient we could have used less building material for the book tray, this would decrease the resistance causing the machine to be more efficient.