3:02 Back Dropping a Ball File Details PHYS 100A Determine acceleration of a ball after it is dropped. 1. Record the time it takes for the object to fall 0.80 m. To do this, you will take a video of the ball falling on the ground from the height of 0.80 m three times. Then you will find out the time by analyzing your videos as follows: You need to upload the video file to your computer and analyze it. First, find the frame rate or FPS (frames per second): In "File Explorer", right click on the video file, select "Properties" then "Details", and copy the frame rate (round it to an integer) to your report. A common frame rate is 30 FPS, which means that each frame in the video is 1s/30 = 0.033333 seconds apart. We will use half of it or 0.016667 seconds to be the uncertainty in time t. (Note we kept 5 non-zero digits when calculating, and only at the end of our calculation we wound to the right number of sig. figs.) Play the video using software that can play each frame, like "Windows Media Player". Use "Right click - Enhancements - Play speed settings" to play the video frame by frame using the buttons, and locate two frames when the marble is at either end of the ruler (which should be 0 and 80.0 cm). Read the positions of the marble in each frame and count the number of steps between them. This information allows us to find the distance d (which should be 80.0 cm) and the time t. An example of how to report your video analysis is as follows (this is from one of my previous colleagues, Yu Sue at Langara College, which she wrote on a totally different lab): The frame rate of my video is 30 FPS. There are 17 steps between (27.7 ± 0.2) cm and (0.2 ± 0.3) cm; Distance d = 27.7 cm - 0.2 cm = 27.5 cm. Time for this distance t = 17×1s/30 = 0.56667 s, dt = 0.5×1s/30 = 0.016667 s= 0.02 s. It is very important that you read the marble's position from the same edge, and count the number of steps rather than the number of frames: there are 17 steps between 18 frames. 3. Do the process above for three falls and fill in the table below (remember to use the proper # of sig. figs.) Trialt (s) 1 2 3 What is the mean time, mean = (t₁+2+3) / 3? 4. Compare this time to theory (free-fall). You need to show all the steps (diagrams, coordinates, parameters, equations with symbols, solving for unknown) below on how you found the falling time from kinematics equations. ◄ Previous Dashboard Calendar To-do 2 67 Next ▸ Notifications Inbox