Define The Problem
We had to make a compound machine that could preform a certain task. Ours had to lift a ping pong ball up to 2 ft. one of the biggest constraints was the fact it had to be made up of 3 different simple machines
Generate Concepts
We decided to use the first idea which was the ramp the wheel and the pully
Develop a Solution
Construct and test the Prototype
The inclined plane to the right has a mechanical advantage of 1.41:1. The fixed pulley at the top has a mechanical advantage of 1:1. Finally, the wheel and axle on the left has a mechanical advantage of 240:1. This gives an overall ideal mechanical advantage of 338.4:1
Evaluate the solution
First, our design wasn't perfect so be had to make some changes to the inclined plane. Before we fixed it the slope of the plane was too steep. We also had to reinforce the plane because the weight made the metal bend. Last we had to add railing to the side so the ball and cup do not fall. The differences between our ideal and actual mechanical advantages is immensely slim. In order to find the actual mechanical advantage of the system, we had to set up a proportion to find the force of effort. This ruled out any of the interfering forces by friction or air resistance
Present the Solution
This is the railings that were made to prevent the cup from falling off
This is the top of the inclined plane and the pulley system. The pulley was used to pull up the cup.
This is the wheel and axle that when turned would , using the pulley, pull the cup up the inclined plane.
I had a very good time working on my second VEX lab. It was easy to build, Efficient, and we didn't run run into any problems. Some mistakes we made was with how to strengthen the inclined plane, which was tricky to do. Also the ball kept falling so we had to add railing to our build .
Conclusion
The easiest mechanism to determine the mechanical advantage of was the fixed pulley because it is always equal to one.
It was most difficult to record the mechanical advantage of the inclined plane. Since it was so long and so tall, it was difficult to accurately measure it, with only rulers.
I would estimate the input force to be about 20 grams and the output to be over 300 grams. Our actual mechanical advantage overall was 338.54, so we would have been able to pull much heavier items with our compound machine. The cup and ball together weighed about 6 grams, but with all of the friction I would estimate about 20g of input force. (This is from luke but i think this is how it is calculated)
We could have added more strings to the pulley or we could have came up with a different combination of simple machine that would be more mechanically efficient.