Introductory Physics I: Mechanics and Wave Motion Problem Set 2

1. Assignment 2 on our MasteringPhysics course site.
2. Y&F Chapter 2 problems:
   1. 2.15
   2. 2.34
   3. 2.44
   4. 2.95 (hard)
   Y&F Chapter 3 problems:
   1. 3.4
   2. 3.13
   3. 3.56.  The physics is the same in 11th and 12th editions, but the storyline changes from launching a burning match into a wastebasket to filling a bucket with a stream of water.  Perhaps the publisher was afraid of lawsuits.
3. Last year I duct-taped one of the demonstration lab accelerometers to the luggage rack on the top of my car and recorded data as I drove.  I went out to Stadium Drive by the UMass football stadium, stopped, and put the car in second gear.  From a dead stop, I floored the gas pedal from about t=3s to about t=14s, then slammed on the brakes and stopped in about 4 seconds.  Download the a_x  data here and import into your favorite math program (for instance, for older Excel use File > Import .  For newer Excel use File > Open, but you may need to ask Excel to accept non-.xls files). Then:
   
   1. Plot acceleration vs time.  Notice that the acceleration looks pretty constant but the braking does not, probably because my antilock brakes started pulsing. 
   2. Calculate velocity and distance as a function of time.  You may check your answer using the constant-acceleration formulas, but you should perform the integration numerically.  If you've never done numerical integration before, copy an example from the web or adapt this little Excel spreadsheet.  Do not turn in a long table of numbers, just print out a plot of v vs t and x vs t.
   3. What was my peak speed (in miles per hour)?  Remembering that I was basically driving in a parking lot, your answer should explain why I gathered this data late at night with my lights off, after checking there were no police in the vicinity.
   4. How far did I travel?
4. Superman is able to "leap tall buildings in a single bound".  How fast does Superman need to be moving when he leaves the ground in order to leap over a tall building, assuming that "tall" means 1/8 mile?  You may check your answer if you wish by listening to the interview with the author of The Physics of Superheroes.  The interview will also answer the question you should be asking right now: "Why does Superman need to leap buildings when he can fly?"

Y&F Chapter 2 and Chapter 3 up to and including section 3.3.