Kinematics Exercise 4: Falling Ball

Note: your results from this exercise will be handed in individually via CrowdMark. Remember that while you may discuss the physics with your peers, your work must be your own (do your own measurements, calculations etc.).

4.1 You have been provided with the motion diagram of a falling ball taken at time intervals of 1/30^th of a second. (Note: you don’t have any more information about this ball, it’s not necessarily on Earth!)

Measure (as carefully as you can) the position as a function of time. You may do this in one of three ways. One, on a printed sheet with a ruler, which can be downloaded below.

Strobe photo of falling ball with ruler (PDF)

Two, from your computer with the picture of the ruler provided beside the ball (if you are using the Word file, you can move the horizontal line up and down as a guide),

Strobe photo of falling ball with ruler (Word)

Three, you can do it directly on the press book using the interactive element at the bottom of the page. Click the H5P element to expand it. Note this interactive feature may not be compatible with all browsers, in which case you should use one of the aforementioned methods (PDF or Word).

Enter your data into Excel. Label your columns “time (s)” (in cell A1) and “position (cm)” (in cell B1). Type in your first two data points in column A as zero and 1/30 (remember to change the cell format to “Number” otherwise you’ll get a date), and then use autofill to calculate the rest. You will then have to enter your position data into column B manually.

Plot your position-time graph. Make sure to label your graph and axes appropriately.

4.2 You can now use your measurements to calculate the approximate velocity as a function of time for each 1/30^th of a second time interval. Label column C as “velocity (cm/s)” and have Excel calculate ∆x/∆t for each adjacent set of position data. (Remember: you only need to put the equation into the spreadsheet once and then use the autofill function to do the rest!)