Pulley Lab

The BIG Question?

       - How can force be manipulated using a simple machine?
       - What pattern do you observe regarding the relationship between force and distance in a simple machine?

• In the Pulley lab, we were asked to figure out how force can be manipulated using a simple machine. To find this, we first found that it takes 2 Newtons to lift the brass mass 10 cm off the ground without using the pulley system. Then we used the pulley and found that it only takes about 1.2 Newtons to lift the same brass mass 10 cm off the ground. The length of the string came out to be 27.5 cm. We found out that the force can be manipulated by the distance and the angle of the string you pull to lift the weight. 

• In comparison to Part 1, we noticed that the amount of force you have to apply is less when you have to use a greater amount of string to pull using the pulley system.

• HOWEVER, we also learned that there's alway a trade off in life... according to this experiement, the more distance you use, the less force is needed to apply. 

• To graph our data, we had to convert the distance from centimeters to meters.
• 10 CM = 0.10 M
• 27.5 CM = 0.275 M

• Here is a picture of my group's bar graph:

• Once we graphed our data, we saw a relationship between the two areas. It fits the pattern of the more distance you use, the less force there is. The area shown on the graph measuring force vs. distance with out a pulley has a higher yet shorter bar, showing greater force and less distance. The area shown on the graph measuring force vs. length with a pulley has a lower, but longer bar showing greater distance and less force.

• To write the area as an equation, we started with Area = Base (Height), which would be Area = Distance (D) x Force (F). In the data we found that 1/2 F = 2x D. The units this equation would be represented by would be Newtons (Force). Soooo.....
• (2N)(0.1M) = 0.2
• A = 0.2NM
• A= F(D)

• We also learned that energy is measured in Joules (J), and work (W) is energy transferred by applying a force over a distance. Therefore, energy (J) is the ability to do work.

• W = FD

***No matter how big the distance or the force is, you always use the same amount of energy***

• Real Life Connection: Elevators
• Imagine what it would be like to work in a 100 floor building and you worked on the one hundredth floor. Each flight you had to walk up stairs every morning and every night... That's what your day would consist of if elevators weren't invented, specifically the pulley system! Elevators use the pulley system to take you up and down to get to the floor you need to be on.