PHYS 1401 Lab-8: Torque Name: Torque Torque is the twisting effect caused by one or more forces. Torque is a twisting action that produces rotational motion or a change in rotational motion. To understand torque (rhymes with dork), hold the end of a meterstick horizontally with your hand. If you dangle a weight from the meterstick near your hand, you can feel the meterstick twist. Now if you slide the weight farther from your hand, the twist you feel is greater, although the weight is the same. The force acting on your hand is the same. Lever arm is the distance between the point of application of the force and the axis of rotation. It is the shortest distance between the applied force and the rotational axis. We are intuitively familiar with torques while playing on a seesaw. Kids can balance a seesaw even when their weights are unequal. Weight alone doesn't produce rotation. Torque does, and children soon learn that the distance they sit from the pivot point is every bit as important as weight. Torque is calculated using the equation: Torque t = Force F X lever armi = Fr sin 0 We are hanging mass on the meter stick. Force is the weight of the object. Lever arm is the distance between the fulcrum and point where mass is hanged. When the torques are equal, making the net torque zero, no rotation is produced. The meter stick will be in equilibrium. Mathematically, Tclockwise = counterclockwise Procedure 1. Open the PhET Simulation Balancing Act https://phet.colorado.edu/sims/html/balancing- act/latest/balancing-act en.html 2. Choose "Balance lab" tab. Play around with the simulation for a few minutes to understand/ explore the functionalities of the different components.Procedure 1. Open the PhET Simulation Balancing Act https://phet.colorado.edu/sims/html/balancing- act/latest/balancing-act en.html 2. Choose "Balance lab" tab. Play around with the simulation for a few minutes to understand/ explore the functionalities of the different components. 3 . Select the following options in right corner of the screen: Mass Labels, Level, Rulers 4. To check if the wooden board is balanced, remove supports under the board by toggling the switch at bottom of the screen to right. Case-1: Consider this situation without using the simulation: 1 80 kg 20 ko D 1.75 1.5 1.25 1 0.75 0.5 025 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Meters Meters80 kg 20 kg 1.75 1.5 1.25 1 0.75 0.5 025 Q.25 0.5 0.75 1 1.25 1.5 1.75 2 Meters Meters 1. Predict what will happen when the supports are removed and explain your reasoning. 2. Predict what will happen if the 80 kg adult was further from the pivot (more right) and explain your reasoning 3. Predict what will happen if the 20 kg child was closer to the pivot (more right) and explain your reasoning 4. Test your predictions in the Balance Lab. Make notes about any ideas you have that need to be changed. 5 . What are some rules you could use to make predictions for other situations where masses are on a balance? Case-2: Place 5 kg fire extinguisher at 2 m mark to the left of the pivot. Where should you place the 10 kg trash can to balance the board? Show your calculations. 5 kg 10 kg 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Meters Meterscounterclockwise = clockwise Tclockwise = [1; Tcounterlockwise = T2 migr1 = M2gr2 (We can cancel "g" as g is present in each term of the equation) mill = m212 Masses mi and my are given; ri = 2 m; unknown r2 =? 2 Case-3: Place 5 kg brick and 10 kg brick to the right of the pivot, and 15 kg to the left of the pivot. Where should you place these bricks to balance the board? Show your calculations. 15 1.75 1.5 1.25 1 0.75 0.5 0,25 0.25 0.5 0.75 1 1.25 1.5 1.75 2 Meters Meters counterclockwise = clockwisecounterclockwise = clockwise Tclockwise = T1 + 72; Tcounterlockwise = T3 T1+ 12 = 13 mign] + m2gr2 = mag13 (We can cancel "g" as g is present in each term of the equation) militm212 = m313 Solve for r3. Given: m1 = 10 kg, m2 = 5 kg, m3 =15 kg Finding unknown masses Choose "Balance Lab" tab. Select the following options in right corner of the screen: Mass Labels, Level, Rulers In the "Bricks" section on the right of the screen, click on the right arrow. Keep on clicking to the right until you see "Mystery Objects". Bricks Mystery Objects 5 kg 10 kg 15 kg 20 kg Find out the mass of each of the Mystery Objects "E", "F", and "G" by balancing each of these against the bricks of known masses. Use only one brick of known mass. For each Mystery Object, paste a screenshot of balanced seesaw and show all calculation steps. 3Mystery Object "E" Screenshot of balanced seesaw: Calculations: Mystery Object "F" Screenshot of balanced seesaw: Calculations: Mystery Object "G" Screenshot of balanced seesaw: Calculations: Analysis Questions 1) When the meter stick is pivoted at its center of gravity, it is in equilibrium, i.e., perfectly horizontal. If it is pivoted even a few millimeters away from its CG, it tips to one side. Why does this occur? 2) Write some (at least 3) applications of this experiment that could be used in your daily life.Formal Lab Report A lab report should contain the following: 1) Objective of the experiment. Read the experiment so you know what you will be doing. By reading the experiment, you will find out what your objectives are. These should be written in at least 3-4 sentences in your own words. 2 ) Screenshots: Insert a screenshot for each of the mystery objects. Take a screenshot of the PhET simulation once the meterstick is balanced. A screenshot will help the person report can visualize the set-up of the apparatus. 3) Data in tabular form. Draw your own data table for Mystery objects "E", "F", and "G". Make sure to include units for all quantities measured. Remember to list the columns in the order in which the measurement was taken. This means that data which are recorded first go in columns towards the left. Calculations made with the data go in columns towards the right. 4) Calculations: Show calculations so that the reader can see how the results were obtained. Put the calculated data in tabular forms. 5) Analysis: Answer the questions in complete sentences and in your own words. 6) Conclusions: This should be a succinct summary of what you learned in this lab. Do not summarize the procedure but focus on the results. Include the numerical value of the final result in a sentence or two. Were the results as you had predicted, or did you find some surprising details? A short paragraph will be sufficient for the conclusion