EXAM 1                  October 4, 1989            PS 207

If you need a constant not given here or do not understand a
problem, please ask me about it.  Remember to include diagrams
and explain your reasoning.  No notes, books, etc. may be
used during this exam.


                          2
             g = 9.8 m/sec 
                                        -31               
   The mass of the electron is 9.11 x 10    kg




1.  (10 points).  State and explain how to remember (not
necessarily derive)

 (a).  The relation for the position of a particle as a
function of time for motion in one dimension with constant
acceleration.

 (b).  The relation giving the magnitude of the
centripetal acceleration for a particle moving at constant speed
v  in a circle of radius  R.



 The remaining problems count 30 pounts each:



 2.  A stone is thrown straight upward with a speed of v .
                                                        0    
How high does it go?  How long does it take to rise to its maximum

height?


 3.  (From homework)  A child whirls a stone in a horizontal
circle 2.0 m above the ground by means of a string 1.3 m long.
The string breaks, and the stone flies off horizontally, striking
the ground 9.0 m away.  What was the centripetal acceleration
during the circular motion?


 4.  An elevator ascends from the ground at uniform speed.  At

time  T  , someone drops a marble through the floor.  The marble
       1             
falls with uniform acceleration  g  and hits the ground  T   sec
                                                          2  
later.  Find the height of the elevator at time  T  .
                                                  1