EAS199C Homework 2
(with thanks to Living with the Lab for modified homework content)

  1. Two cables support an unknown weight. If the tension in cable BC is 100 lbs, then what is the unknown weight? Don’t forget to draw a FBD.

  1. Two cables support a weight of 5 kN as shown in the diagram above. Determine the force in each cable. Be sure to draw a FBD and write equations for the components of each of the forces.
  1. A trampoline with a 10-foot diameter circular mat has 50 springs equally spaced around its circumference. If a 110 lb. girl produces a downward force of 250 lbs at the bottom of her jump (when the springs are stretched the most) causing the springs to angle down at 5°, then what is the average force in each spring? Assume that she lands in the center of the mat and that 50 separate but equal forces act to support the girl’s peak impact force.

4. Consider the ADXL335 accelerometer described in class.

  1. Find the data sheet online (a PDF file) by searching for ADXL335. List three of the applications of this sensor as specified on the data sheet.
  2. Using the calibration data presented in the PowerPoint presentation on the website (xaccel=627 when +x is pointed upward, xaccel=514 when +x is flat, and xaccel=401 when +x is pointed downward), what angle does the +x make with the horizontal direction when the output of the accelerometer is 528?
  3. If the +x axis of the accelerometer is oriented at -50° from the horizontal, what will the Arduino sketch output for xaccel?

5. Generate bug #2 for your “Bug List.” Remember that a bug can be something that doesn’t work quite right or that could be improved, something that bothers you, or things that you notice others struggling with. For your homework, please name the bug, write up at least a two sentence description of the bug, and provide pictures when it makes sense to do so. You don’t need to try to find a solution to the problem at this point. Try to think of bugs in different categories as you build your bug list. For example, find bugs related to major life activities (recreational, occupational, tasks of daily living, transportation, communication, learning) and bugs affecting special people groups (disabled, senior adults, children).

5. (due in Class 4) Using the Internet and other sources, learn about ethical dilemmas surrounding technology in international development. Focusing on one or two dilemmas, write up two or three paragraphs describing what you have learned (from ½ to 1 page single spaced); be thinking about the impact that international development might have on your career. We expect you to spend about one hour completing this problem; this is not meant to be an exhaustive study of the topic.