Answer Happy

In PHYS 140, Group 1 measures the radioactive decay rate of KCl to be 33.0+3.6 counts per minute (CPM). One group mate suggests that they also measure the background radiation in order to see if other sources of radiation might be biasing the result. The radiation in the background is found to be 10.7+2.2 CPM. (a) Calculate the unbiased decay rate of KCl. Express your answer with the appropriate significant digits. R= CPM (b) What is the uncertainty in your result? Express your result with the same number of decimal places as your result in (a). SR = CPM
The position of a dynamics cart under the influence of no net force is measured as a function of time. The following data are collected: t(s) At (s) Ax (m) x(m) 0.04 0.0 1.0 1.05 2.0 2.00 3.0 3.09 4.0 3.98 = 5.0 4.90 The uncertainty in x and t is x = +(4.0% of the measured value + 0.05 m) and t = + 0.1 s. The columns for At and Ax are empty - you will fill them in on your own. What is the average velocity of the cart over the first five seconds? Answer: 0.972m+1 Check What is the uncertainty of the position at t=3.0 s? Don't forget your units in your answer.
1. Open Microsoft Excel and create a new file. Copy the data and all four columns into the sheet 2. Create a scatter plot of position versus time. Label your graphs appropriately. 3. Include both vertical and horizontal error bars. To insert the error bars: (a) Click anywhere on the chart with your mouse, then click the Chart Elements button that appears (the green cross in the top-right corner). (b) Check the box next to Error Bars; vertical and horizontal error bars should appear on the graph. (c) Double-click on one of the horizontal error bars; on the right side of the screen, the Format Error Bars menu should appear. Make sure the button with the three vertical columns is selected. (d) Locate the "Custom" button in the menu. Choose it, and press the "SPECIFY VALUE" button. Select the values entered in the t column for both "Positive error value" and "Negative error value". (e) Repeat for the vertical error bars corresponding to x using your values of x. 4. Determine the slope of the graph using the trendline option. Be sure to display the equation on the graph. Write down the value of the slope below to three significant digits. (You should recall clearly from PHYS 140 that the slope of the graph represents the velocity, v, in accordance with our model of motion in the absence of a net force.)