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physic lab 145.1 prelab 10 pdf link if needed http://www.physics.qc.edu/files.ph

ID: 2010750 • Letter: P

Question

physic lab 145.1

prelab 10 pdf link if needed http://www.physics.qc.edu/files.php
You will be allowed three submissions for this question. Assume the ruler is exactly 1 m long, and the mass hangers have negligibbe mass.

a) Suppose the ruler in procedure 2 is asymetrical, and it is balanced at the 41.3 cm mark (at the center of mass). Now, mass M is hung on the ruler at the 100 cm mark. Where must you hang mass 1.69M so the system remains in equilibrium?
At the _________________ cm mark

b) The method of procedure 2 can be used to accurately determine the mass of a light coin (as in procedure 4). Suppose the ruler is perfectly symmetrical, and it balances at the center. The coin of unknown mass is placed at the 0 cm mark, it is balanced by a mass m = 22.9 g placed at the 76.6 cm mark. Find the mass of the coin.
__________________________ g

c)Suppose the ruler in procedure 3 is asymmetrical, balancing at the 57.2 cm mark. The ruler is now supported at the 45.3 cm mark, and a mass of 455 g is placed at the 31.3 cm mark. Find the mass of the ruler. ______________________ g

Explanation / Answer

(a) Taking moments about the center of mass: Clockwise moments = Anticlockwise moments M * ( 100 - 41.3 ) = 3 M * ( 41.3 - x )                          58.7 = 123.9 - 3 x                                x = 21.73 cm Ans: 21.73 cm (b) Taking moments about the center: Clockwise moments = Anticlockwise moments 22.9 * ( 76.6 - 50 ) = M * 50                                M = 12.18 g                           Ans: 12.18 g (c) Taking moments about the support: Clockwise moments = Anticlockwise moments M * ( 57.2 - 45.3 ) = 455 * ( 45.3 - 31.3 )                             M = 535.3 g                           Ans: 535.3 g Taking moments about the center: Clockwise moments = Anticlockwise moments 22.9 * ( 76.6 - 50 ) = M * 50                                M = 12.18 g                           Ans: 12.18 g (c) Taking moments about the support: Clockwise moments = Anticlockwise moments M * ( 57.2 - 45.3 ) = 455 * ( 45.3 - 31.3 )                             M = 535.3 g                           Ans: 535.3 g Taking moments about the support: Clockwise moments = Anticlockwise moments M * ( 57.2 - 45.3 ) = 455 * ( 45.3 - 31.3 )                             M = 535.3 g                           Ans: 535.3 g