This discussion focuses on calculating the mass of a meter stick using torque principles. The fulcrum is positioned at the 60 cm mark, with a 100 g mass placed 30 cm from the fulcrum and a 50 g mass placed 43 cm from it. The net torque is established as zero, leading to the equation involving torques from the two masses and the gravitational torque acting on the meter stick. The calculated mass of the meter stick is approximately 85 grams, which is close to the actual measured mass of 97 grams, indicating potential measurement errors in the lab setup.
PREREQUISITESStudents in physics, particularly those engaged in laboratory experiments involving torque and equilibrium, as well as educators seeking to enhance their teaching methods in mechanics.
Torque = rfsintheta but in this problem sintheta=1. I found the torque of gravity to be .0833 from that equation if that's cprrect? So I have .0833 = .1 X f. Solve for f and get f = .833 N. I divide this number by 9.8 to getNathanael said:Right, gravity acts everywhere, but it effectively acts on the center of gravity. In other words, if you treat the full force of gravity acting only the center of gravity, then it will be the same as if you treat gravity as being spread across the object. So we can say the force of gravity (9.8 X mass) acts on the center of gravity.I mean the mathematical definition. How is torque defined with numbers? If you know a force, and you know the distance it acts, then what is the torque from that force?
Put this all together and take some time to try to solve the problem.
Good. 85 grams. The actual weight was 97 grams? You're not doing anything wrong. You said it was a lab, right? So you actually measured these distances? That can account for the error.khannon5 said:.085 kg but this can't be right what am I doing wrong?
Ok thank you so much. I really appreciate your timeNathanael said:Good. 85 grams. The actual weight was 97 grams? You're not doing anything wrong. You said it was a lab, right? So you actually measured these distances? That can account for the error.
Look at it like this... If the 50g mass was actually at 42.5 cm and the 100g mass was actually at 30.5 cm, then you would get an answer of 92.5 grams. (Not to mention if the fulcrum is not exactly at 60 cm! That's probably where the error really comes from!)