HRW - PROBLEM SUPPLEMENT #1

        #78 was originally posted with a typo (the 60 cm side was
        incorrectly given as 30 cm).  It was corrected on 4/1.  GBA

        78.  The picture for this problem is an isosceles triangle.  The
             two equal sides have lengths of 50 cm each, and the other
             side has a length of 60 cm.  The sides represent massless
             rods connecting three particles located at the vertices
             of the triangle.  The mass at the vertex where the two 
             equal sides come together has a value of 0.40 kg.  The other 
             two masses are each 0.80 kg.  A point P is located at the
             center of the 60 cm side.  The entire triangle is to be
             rotated about an axis perpendicular to its plane and passing
             through point P.  How much work is required to take the body
             from rest to an angular speed of 5.0 rad/s?

        89.  A wheel rotates with angular acceleration 
             alpha = 4at^3 - 3bt^2, where t is the time and a and b are
             constants.  If the wheel has initial angular velocity
             omega_0, write expressions for (a) the angular velocity,
             and (b) the angular position of the wheel as functions of
             time.