What Went Wrong with Calculating Pulley Efficiency?

In summary, the conversation discusses a lab on pulleys and the attempt to find the efficiency. However, the measurements taken do not make sense and it is realized that the distances measured were incorrect. The math was done correctly, but the lab results are inaccurate.
  • #1
livvy07
6
0

Homework Statement



we did a lab on pulleys. The weight lifted was 19.62 N. It rose 0.20 meter with us applying a lifting force of 11 N and pulling the rose a distance of 0.16.


The Attempt at a Solution


I tried to find the efficiency of the pulley, so E=work out/work in
so work out=FD=(19.62)(0.20)=3.92
and work in=FD=(11)(0.16)=1.76
yet the work output can't be greater than the work input, so I'm clearly doing something wrong.

Any ideas? Is it a math error or bad lab results? Any help would be great :)
 
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  • #2
It's not a math problem. Those measurements don't make sense. How did you measure the applied force and distances?
 
  • #3
oh no. That means the whole lab is wrong, but I'm doing the math right?
We measured the applied force with a spring scale and the distances with a ruler. i think the distances are completely wrong now...
 
  • #4
livvy07 said:
That means the whole lab is wrong, but I'm doing the math right?
Yep, your math is fine. :frown:
 
  • #5
oh well. Thanks for the help though! Guess I'll have to start making up numbers
 

FAQ: What Went Wrong with Calculating Pulley Efficiency?

What is a pulley in physics?

A pulley in physics is a simple machine that consists of a grooved wheel and a rope or cable. It is used to change the direction or magnitude of a force, making it easier to lift heavy objects or move them horizontally.

How does a pulley work?

A pulley works by distributing the weight of an object over multiple ropes or cables, reducing the amount of force needed to lift the object. As the rope is pulled, the weight of the object is transferred to the pulley, which then transfers it to another rope or to a fixed point.

What are the different types of pulleys?

There are three main types of pulleys: fixed, movable, and compound. Fixed pulleys have a stationary axle and are used to change the direction of a force. Movable pulleys have a movable axle and are used to reduce the amount of force needed to lift an object. Compound pulleys are a combination of fixed and movable pulleys, and are used to both change the direction and reduce the force required.

How do you calculate the mechanical advantage of a pulley system?

The mechanical advantage of a pulley system is calculated by dividing the load force by the effort force. For example, if you are using a pulley system to lift a 100 kg object with an effort force of 20 kg, the mechanical advantage would be 5 (100 kg / 20 kg = 5).

What are some real-life applications of pulleys in physics?

Pulleys are used in many everyday applications, such as elevators, cranes, and flagpoles. They are also used in more complex machines, such as cars and construction equipment. In addition, pulleys are used in physics experiments to demonstrate concepts such as work, force, and energy transfer.

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