I have to do a write up for a lab we did in physics class. We were working with pulleys. How do I find the total work done, and percent error for work done? Also, how do I find the number of strings involved?
2007-03-19 08:55:23 · 2 answers · asked by Anonymous in Science & Mathematics ➔ Physics
We will definitely need more information. Work is force times distance, so if you measured a constant force during the lab, you need to multiply that times the distance the rope moved while that force was applied.
If you didn't measure force but just had weight hanging off of pulleys, then the work done is the force (m*g) times the distance the weight was lifted (h), W = mgh. Note that if the weight was lowered, the work would be negative.
The percent error is something you have to estimate. If you were measuring force, my guess is the force wasn't always constant... so you get error since you're not sure exactly what the force really was during the entire process. Or you can't measure distance precisely.
No idea what you're talking about with strings.
2007-03-19 09:04:19 · answer #1 · answered by Tom 3 · 0⤊ 0⤋
The work done is the force applied (in 'Newtons'), multiplied by the distance the objects were moved (in metres). The percent error on a measurement is the largest amount by which your measurement could be 'off', divided by the size of your measurement, x 100%.
For example, if you measure a distance of 50 cm, but your ruler is only accurate to 1 cm, then your measure could be 'off' by up to 0.5 cm. So, the % error would be:
0.5/50 x 100% = 1%
That's all I can tell you with the info you've given.
2007-03-19 16:07:28 · answer #2 · answered by Ian I 4 · 0⤊ 0⤋