Rotational Equilibrium Names: Equipment: Meter - Stick Fulcrum Hanging Mass Set (1) knife-edge clamps for fulcrum (3) closed string loops to hang masses from Torque: Torque = force x lever-arm Rotational Equilibrium: An object is in rotational equilibrium when the net torque acting is zero. Units: The SI torque units are meter.newtons (m.N). Since the force supplied in this lab is the weight-force which is proportional to the mass, we will use units of cm.gram. This unit can easily be converted to m.N if necessary. Procedural Notes: Perfect balance of the meter stick is not needed to obtain good results. Once it is close to balanced you can move on. Stay on the same side of the experiment so your definition of clockwise (CW) and counterclockwise (CCW) will not change. 10cm 40cm 50em M m Place the fulcrum at the 50cm mark of your meter stick. Hang M=500 grams at the 40cm mark. Hang m=300 grams on the opposite side of the fulcrum at a location such that the meter stick is nearly balanced. Record 71 = (7 cm for the smaller mass m.Calculate the torques in cm-grams due to the weights: cm . gram "cow = (10cm)(500gram) = 5000 TCW = (r )(300gram) = 5100 . cm . gram If the torques are not equal to within +/- 5% repeat the experiment. Keep the larger mass M as it is and change the smaller mass to m=200 grams. Move m=200 grams until equilibrium is achieved. Record the new value of n = _ 25 cm Calculate Tow = (71 )(200gram) = _G ooo _ cm . gram . If the torques are not equal to within +/- 5% repeat the experiment. Based on this experiment, we can say that: A smaller force needs a (circle: greater lesser ) lever arm to provide the same torque as a larger force. Remove all hanging masses. Move the fulcrum to the 20cm mark. Hang m=200 grams at a location which places the meter stick in equilibrium. m Measure 71 = _ (( . 5 cm for hanging mass. m. Use the torque balance equation to calculate the mass of the meter stick. (r =((.5 )(200gram) = (50cm - 20cm)(m stick) 1 st Calculation of stick = 76 . 7 gram Move the fulcrum to the 35cm mark. Hang m=200 grams at a location which places the meter stick in equilibrium. m Measure 71 =_. 25.5 cm for hanging mass m. Use the torque balance equation to calculate the mass of the meter stick. (71 =_5.5 )(200gram) = (50cm -20cm)(m stick)2nd Calculation of stick = gram Lab Scale value for: I stick = gram Comment on the most likely causes of experimental error. disproportioned meter stick meter stick is not uniformed