The purpose of this experiment was to help understand torque by not only measuring it but also by manipulating and adjusting the weights experimentally. Procedure In order to perform all the procedures a few instruments were required a meter stick, a triple beam balance, suspension clamps and their stirrups, a knife edge, as well as weights of 50 and 100 grams and a spring scale.
The meter stick was weighed (without the clamp), and its center of gravity was found (it’s not usually exactly at 50cm), the 6 clamps were weighed as well.
For the first part the meter stick was put on 35cm and a 100g weight was adjusted until the center of balance was found, the position was recorded, this was than done with 150g and 50g. Once the values were recorded the weight of the bar was calculated and the average was found. For the next part of the experiment three weights were attached anywhere on the bar, the center one was adjusted till there was equilibrium and than the force was measured with a spring scale.
The numbers were recorded and the weights of down and upward forces were measured as well as the clockwise and counter clockwise torques. For the last part of the experiment six clamps were arranged on the bar( with weights on them ) so that one was at 10cm and one at 90cm and the rest were spread in between , one end was supported by the knife edge and the other by the spring scale.
The forced shown by the scale was recorded, the ends were than switched and the force was once again recorded.
Calculations were than done to verify the sum of the torque was that of the reading on the spring scale as well as that the total sum of the weights was compared via calculation to the upward force shown. Data/Analysis Part I: Prep Part II: Calculating the weight of the meter bar by balancing torque (mb): (mc= mass of clamp, g = acceleration due to gravity) Table 1: Determination of Meter Weight by Balancing to Torque (Experimental) m= mass of weights (g) x= Clamp Position from knife edge (cm) mb= Weight of Meter Bar from Balancing Torque (g)
Position on meter stick (cm) r= position from axis of rotation (m) (N*m)96 Questions: The motion of the rigid system will move up in the counter clockwise direction if the condition for equilibrium is not satisfied in which the spring has greater force. The opposite will happen if the meter bar and weights have a greater force than the spring. The same goes for the Torque.
If the second condition for equilibrium is not satisfied and there is greater torque of the spring, the system will move in the counter clockwise motion and will move clockwise if the Torque is greater for the meter bar. The motion of the rigid system will move in the same fashion as described above if neither of the conditions for equilibrium are satisfied. If there are equal numbers of suspension clamps on each side of the support with the same weight, their weights can be omitted from the calculations because the weights can be factored out and be eliminated from the way the force and torque equations are set-up.
Regardless, they should total to zero. When the center of gravity of the meter bar was determined in Part I, the bar was supported at a point coinciding with the center of gravity. If the clamp were to have been inverted, where the bar is supported at a point above the center of gravity, you wouldn’t een be able to balance the meter bar because it is not in the center of gravity it would just be slack and hang down. Therefore you wouldn’t even find the accurate position where it is level.
This would have skewed the results, making inaccurate readings and calculations. In part IV, if the meter bar were to be held at an incline of 30 degrees angle above the horizontal by the spring balance, the spring balance reading would remain the same because the force of the spring is just m*g, which remains the same even if you change the angle. The mass and acceleration due to gravity remains constant. However, Torque changes (t=r(F*sin(? )) since angle comes into account. Figure: Conclusion
In the study of this lab, torque was observed by measuring, manipulating, and adjusting the weights on the meter bar. The weight of the meter bar was found by experimentally calculating the torque. Comparing the actual weight of the meter bar and the experimental values, the percent error was only 5. 96%-14. %. This percent error is low enough to be negligible and to confirm the equation used for Part II. In Part III and IV, the forces acting on the meter stick are in the vertical direction.
Since the meter stick was level, the angle was 180 degrees meaning the force acted on the axis on either side of the center of balance. The experiment should have observed that the net force and net torque acting on the meter stick is equaled to zero. However, experimental results show that the net force is not zero. The net torque is not zero as well. However, the net torque value approaches zero more than the experimental values do. Therefore, the torque equation may be confirmed in this experiment, but the force equation cannot because the values are too far from zero.
This may be because the presence of error in this lab is high. Errors occurred in this lab are due to inaccurate measurements of position. It was difficult to keep the meter bar steady to find where the stick is level. Also, there may have been something wrong with the balance and springs because they are very old, rusted equipment and may not work as accurately as they did when they were new. Overall, we were able to understand the concept of torque, even if there were errors in our experiment.