Physics 9/10 or 9/11

1
Physics II 11/4
No Warm-up today. Began in library.
2
Physics II 11/2

• Work on projectile drag spreadsheets.
• Return test retakes discuss answers.
• Use your launcher to determine Cd of a light
  projectile
• Increase launcher power to make drag more
  observable.
• Measure Vo at some chosen high power setting.
  Then measure launch height, and horizontal
  distance traveled. Conduct multiple trials to
  measure both Vo and horizontal distance with
  greater accuracy.
• Measure m A. Assume that ?1.22kg/m3.
• Fiddle with Cd until your graph matches your
  observations (of horizontal distance traveled,
  given the vertical drop from your release point
  to the floor).
• Calculate Cd another way -- by dangling the
  projectile from a string that is suspended from a
  moving stick. The stick is moving with a
  horizontal velocity v. Drag will cause the
  string to deviate from vertical by an angle ?.
• Difficult Problems

3

• What would happen if you dug a hole through the
  center of the Earth, and then you jumped in? How
  long would it take you to fall to the center?
  What would happen then? Ignore air resistance.
• Do you get wetter if you walk slowly in the rain,
  or if you run? How much wetter? Compare the
  volumes of water (in liters) that will smack into
  you at these two speeds, given the following
  assumptions
• Assumptions
• You (the thing getting wet) are a sphere with a
  radius of 0.5m.
• The distance you must travel horizontally in the
  rain, for a distance of one kilometer.
• Your walking pace is 1m/s. Your running pace
  is 5m/s.
• The raindrops are uniform spheres with diameters
  of 2mm.
• The drops are uniformly distributed in the air --
  1000 of them per cubic meter.
• The density of air is 1.22kg/m3.
• The density of rain water is 1000kg/m3