To study static equilibrium of a rotating device.
In this experiment we will show that the sum of all torques will equal zero, r1F1 + r2F2 + r3F3 + .= 0, when the object is in equilibrium. When all the torques add up to zero it implies that the angular acceleration about the pivot axis is zero and will not rotate. .
Procedure:.
First the mass of a meter stick was obtained and recorded. Next the apparatus was assembled and held fast to the table. Next we figured out the center of gravity of the stick by hanging it on the clip from different points until it balanced evenly. String was used to hang the hooks that will hold the other weights at different points on the meter stick. The following 6 sets were used:.
pivot @CG; m1 = 50g @ 20 cm; m2 = 100 g @ ___ cm.
pivot at 20 cm; m1 = ___g @ 10 cm.
pivot @ CG; m1 = 50g @ 10 cm; m2 = ___ g @ 60 cm; m3 = ___ g @ 90 cm.
pivot @ 30 cm; m1 = 200 g @10 cm; m2 = ___g @ 60 cm.
pivot @ 40 cm; m1 = 200 g @ 20 cm; m2 = 20 g @ 60 cm; m3 = ___ g @ 80 cm.
f. pivot @ 40 cm; m1 = 20 g @ 10 cm; m2 = 50 g @ 30 cm; m3 = 40 g @ _____ cm.
We then determined the value of the blank spaces in the sets by moving certain weights different distances from the left end of the stick or adding more weights at the specified distances from the left end of the stick. When the meter stick was horizontal to the table it showed it was in equilibrium. .
Sample Calculations:.
(M1)(R1) + (M2)(R2) + (M3)(R3) = 0.
Example a: (50)(-30) + (100)(R2) = 0.
R2 = 15 cm.
% error = (calculated - measured)/ calculated x 100.
Example b: (440.4 - 438.7)/440.4 x 100 = .39%.
Results:.
The results of our experiment had a small, but yet considerable error. This result may be due to the professor in the make up lab pushing us to hurry and get done.
Error Discussion:.
Sources of error throughout this experiment could have occurred when we balanced the meter stick.