martes, 5 de marzo de 2019

Curso de Física general, primavera 2019


Very dear university colleagues ... perform the following problems:

practice
  1. The following passages are excerpts from "The Long, Lonely Leap" by Captain Joseph W. Kittinger Jr. USAF as they appeared in National Geographic magazine. It is the story of his record-setting, high altitude parachute jump from a helium balloon over New Mexico on 16 August 1960.


An hour and thirty-one minutes after launch, my pressure altimeter halts at 103,300 feet. At ground control the radar altimeters also have stopped on readings of 102,800 feet, the figure that we later agree upon as the more reliable. It is 7 o'clock in the morning, and I have reached float altitude.
At zero count I step into space. No wind whistles or billows my clothing. I have absolutely no sensation of the increasing speed with which I fall.
Though my stabilization chute opens at 96,000 feet, I accelerate for 6,000 feet more before hitting a peak of 614 miles an hour, nine-tenths the speed of sound at my altitude. An Air Force camera on the gondola took this photograph when the cotton clouds still lay 80,000 feet below. At 21,000 feet they rushed up so chillingly that I had to remind myself they were vapor and not solid.
Verify the speed claim of the author. (At this altitude g = 9.72 m/s2.)

2       2 .       A basketball dropped from rest 1.00 m above the floor rebounds to a height of 0.67 m. Assuming the ball is not moving horizontally, calculate its velocity…
a.                  just before it hit the floor on the way down and
b.                  just after it left the floor on the way up.
If the ball is in contact with the floor for 0.10 s determine its acceleration…
    1. on the way down,
d.                  while it is contact with the floor, and
e.                  on the way up.

3     3. A diver jumps from a 3.0 m board with an initial upward velocity of 5.5 m/s. Determine…
 .                    the time the diver was in the air
a.                  the maximum height to which she ascended
b.                  her velocity on impact with the water
4    
      4. Sketch the following graphs of motion for an object thrown straight up.
c.                   displacement-time
d.                  velocity-time
e.                  acceleration-time

Deliver them on a worksheet next Thursday

A fraternal hug

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