Experiment 1 Newton's Second Law O 100 cm Variables Change Friction:0.001 U.005 Change hanging weight(g):1 Change cart weight(g): 10 Change pointer position:0 Start Reset Measurements Time taken to reach Distance (m) ---> pointer(s) : 00:00:00 00.00.00 Pointer Distance (cm) : 0 m : s : ms 0 START STOP Acceleration (m/s?) :0 1 2 3 5 6 For Experiment #1, you will change the mass of the cart but keep the hanging mass/weight (force constant). You will then graph acceleration vs. (1/mass of the set up). You will then use the slope of your excel graph to get an experimental value for the hanging mass and compare that to the actual hanging mass you used in the experiment. Remember to include detailed procedure that shows all the steps that you took to gather data including what values you set the sliders to. Again, the slider above says Change cart weight (g) but it is in grams so you should understand that this is a mass not a weight. The mass of the cart is the independent variable because you change that. Now for all physics labs, the independent variable is the variable that YOU control and is always on the x axis. The acceleration is the dependent variable because the smaller the mass of the cart the greater the acceleration, so acceleration depends on mass. The dependent variable is the variable you are measuring and the variable that is affected by the change in the independent variable. So now let's try to use our data to verify Newton's Second Law. If you rearrange F = m* a you can get a = F/mwhich also equals, with a little algebra.... a =(Flll1/m) IF you look (you can see that the equation above can be treated just like: Y = mx You will graph acceleration (your y value) VS. (1/mass of the entire set up, including the hanging mu yourx value) Now I know I said earlier that the mass of the cart was the independent variable because you are changing the mass of the cart, but Newton's second law requires the net force to accelerate the total mass of the cart plus the hanging mass so the symbol m must represent the sum of both the mass of the cart plus hanging mass in kilograms. You will need to convert (1kg = 1000g) Now a = (F) * (1/m) then the slope of your graph is your experimental value for the constant hanging weight. Remember that weight of that mass is equal to the mass in kilograms times 9.8 m/sAZ. You might need to work backwards to convert the slope which should now be in Newtons BACK into kg and then grams. If you have been working diligently on the other assignments this should not be a problem. So, 50 grams would weigh: 0.05kg *9.8m/s"2 = .49 N And so.... 0.49 N / 9.8m/s"2 = 0.05 kg 0.05 kg * 1000 = 50 g You can compare the slope of the graph you created using excel with the equation in the graph vs. your hanging weight by calculating the percent error and make the hanging weight your aunaLvalue and the slope of your graph is the experimental value. You should show all your data in a data table. You should show all calculations where you use the slope of M excel graph to determine an experimental value for the weight of the hanging mass. Analyzing Experimental Error - The most common way to analyze experimental error is to compare your results with a known value (if available) using the percent errorformula: Actual - Experimental Actual x100 %error = Experiment #2 You can then complete a second experiment where you will now be changing the force (hanging mass, convert to Newtons) and measure the accelerations. You will now be collecting data and graphing acceleration vs. weight of hanging mass and use the slope to find an experimental value for the mass of the whole set up which includes the ca rt's mass plus the hanging mass because all of that is what is accelerating. If you are changing the weight or force on the set ugthen the force is the independent variable (x axis) If the force affects the acceleration then the acceleration is the dependent variable Ly axis). This time you will keep the MASS of the whole set up constant. This is your control variable. Now this is tricky because in order to change the hanging mass and keep the whole set up's mass constant, you will have to take mass off of the little cart and add it to the hanging mass but be sure that the entire mass of everything stays constant for each trial. Or you can take mass off the hanging mass/weight but add it to the cart. This is because the weight of the hanging mass is not only overcoming the inertia of the cart but its own inertia as well. Show all your data in your procedures and include a data table showing all your data. Change the force so that you complete several trials. If you rearrange F = ma, to solve for acceleration you get: a = F/m which could be rearranged to get: a = (1/m) F That means that if you graph acceleration versus force, with force being on the x axis and acceleration being on the y axis, then the slope of your graph should be equal to the inverse of your mass of the entire set up). The you can use that slope to calculate your experimental value for mass. Slope = 1/mass of set up Mass of set up = 1/slope. Be sure to take the inverse of the slope to determine the mass. Remember that this mass will be in kilograms and that you can then multiply by 1000 to get that value in grams to compare to the actual mass in the simulation. These two will only be similar if Newton's Second law is true, and not just some silly fairy tale. That is the point ofa scientific experiment. You can reproduce the same experiment over and over and get the same results. That is how we prove things in science. You can again calculate a percent error for this as well and write a conclusion based on this percent error. Compare your experimental value for the mass of the set up to the measured value. Remember to show data tables for all the data that you collect