EXAM 2                  April 18, 1986               PS 207
     
     If you need a constant not given here or do not understand a
problem, please ask me about it.  No notes, books, etc. may be
used during this exam.

                 2
    g = 9.8 m/sec      

     1.  A nuclear reactor designed and built in Canada (CANDU)

contains heavy water (D O).  In this reactor, the fast
                       2
neutrons are slowed down by collisions with the deuterium nuclei

of the heavy water.  The oxygen in the water is a spectator and

does not affect the collision.  By what factor will the speed of

a neutron be reduced in a head-on collision with a deuterium

nucleus?  Approximate the mass of the deuterium nucleus to be

exactly twice the mass of a neutron.

     2.  (From homework)  A force acts on a particle of mass m 

in such a way that the position of the particle as a function of
                             2   3       
time is given by  x = 3t - 4t + t  ,  where  x  is in

meters and  t  is in seconds.  Find the work done by the force

during the first  T  seconds.

     3.  A road in a small town has a gentle curve of radius      

R = 100 m.  The road is banked by only 1 degree.  The speed limit

is 40 km/hr. After a light snow the coefficient of friction for a

passenger car is  mu  = 0.2 .  If a car is traveling at the
                    s
speed limit, will it skid out of the turn?  At what speed would

cars start skidding?

     4.  A vertical spring has a light platform on its top.  When

a 0.500 kg mass is set on the platform, the spring compresses

0.0245 m.  The mass is now pushed down an additional .0755 m and

released.  How far above this latter position will the mass fly? 

Will it remain in contact with the platform?  Your first step

will be to determine the spring constant  K  in N/m.