Simple Machines: They Make Life Easier

 ~ For this week's lab we studied simple machines. In class, we built a pulley, and tt may have looked easy at first, but it was more complicated than we thought. Using the pulley, we attached the electronic force probe to one end and a 0.2 kilogram brass object to the other and pulled. We did this many times adjusting the speed we pulled at, the length of string we used, and trying to adjust the amount of force we used. One of the goals was to use only 0.5 N of force to lift up the brass object 10 centimeters. It took quite a lot of tries to achieve it, but we were able to do it.

              Trade-Off

 ~ With simple machines, we have found ways to use less force in our everyday lives. BUT, there is always that trade-off. Force and distance are inversely proportional meaning that when force goes up, distance goes down and vice versa. Without a pulley, it took 2 N to lift up the 0.2 kg brass object 10 cm. With the pulley, it took about 1 N to lift up the 0.2 kg brass object 10 centimeters. But we had to increase the length of the string to do this and it was 20 centimeters. We can see that the distance doubled. So we can see "that you really can't have something for nothing."

BIG QUESTIONS:

1. How can force be manipulated using a simple machine?

2. What do you observe regarding the relationship between force and distance in a simple machine? 

          

         -Using a simple machine, we can decrease the amount of force we use. But there is always a trade off. To use less force, you must increase the distance you use. This is shown with the data that we came up with. 

Without pulley: 2 N and 10 cm to lift it up 10 cm

With pulley: 1 N and 20 cm to lift it up 10 cm

The equation we got is A=fd.

       Elevators and Pulleys

Elevators and Pulleys

This link shows us how many people use a simple machine everyday: the pulley for an elevator.