Lab 4 Report Measuring Total Work Done Erin Shin Edgar Dobra Jiatong Chen Xinyang Liu Introduction In this lab we re trying to find the total work done on the IOLab in two different ways There are multiple ways to find total work done which is why we re able to perform different calculations such as work done by spring gravitational energy kinetic energy using the work equation etc In this lab specifically we re calculating the work done by force multiplied by the distance traveled and by the change in kinetic energy It s important to carry out this calculation because if we do find that the friction of the IOLabs wheels does turn out to be important that means that the work done equation must take friction into account Our hypothesis is that the total work done calculated by the two equations will be the same resulting in the friction in the IOLab wheels being small enough that it s negligible Methods We set up the experiment by attaching a wooden block to the IOLab with a string and hanging the block over the edge of the table Then to take our measurements needed for each trial we release it from rest so that the only force acting on the IOLab is the tension from the wooden block as it falls which allows for a constant force By using this method we re able to take the measurements we need Figure 1 Setup of the experiment Our first method we use to calculate the work is by using the work equation of force multiplied by the displacement assuming that the force is constant We re able to get this equation from the fact that the integral of the force equation with respect to the displacement is equal to work If we assume that the force is a constant and we take the integral of that we get that force multiplied by the displacement is equal to the total work done The measurements we need to take is the displacement traveled and the force done on the IOLab The second method to calculate the work done is by measuring the initial and final velocity of the IOLab throughout the course of the table in order to use the total work done by kinetic energy equation listed below 12 2 2 1 2 Mass of the IOLab Mass of the block Results 200 g 0 2 kg 336g 0 336 kg Trial 1 1 164 0 3 0 563 1 671 0 349 0 248 Net Force N Displacement m Initial Velocity m s m s Final Velocity Work by Work by J J Method 1 F d Mean 0 3295 0 00875 Standard Deviation 0 0175 Standard Error 0 00875 Method 2 Kinetic Energy Trial 2 1 135 0 3 0 960 1 860 0 341 0 254 Trial 3 1 046 0 3 0 219 1 592 0 314 0 249 Trial 4 1 046 0 3 0 257 1 620 0 314 0 256 Mean 0 2518 0 002 Standard Deviation 0 004 Standard Error 0 002 Figure 2 Data of the first trial Discussion 2 2 4 33 Friction Force Work done by friction W 0 3295 0 0175 7 8 10 4 d 0 2 0 013 0 3 J 0 2518 0 004 Because our t value is way over 3 we can conclude that friction is not negligible and must be included in the work calculated By taking a new measurement for the frictional force we were able to estimate that about 7 8 e 4 J has been done by friction Conclusion From the data above we are able to conclude that the work calculated by F d and change in are not equal and are not related to each other The frictional force on the wheels of the IOLab is not negligible in this experiment This is because we believe that friction applies an additional work to the total resulting in a higher work calculated by the force times distance compared to work calculated by kinetic energy We believe that while this may be true in most circumstances we also believe that if the pulling force of the block is large enough the work done by that force will be big enough that friction will be negligible at some threshold For example we can use a block with larger mass to pull the IOLab Team Contributions Xinyang Also helping with data collection but also helping calculate all values Jiatong Helped revise the report finalize any values and helped clarify the report Edgar In charge of IOLab data collection and helping us calculate means Erin Explaining methods and introductions clarifying methods procedures Everyone Contributed to writing the report
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