On the review for energy and momentum, 4a: the centripetal force for point A is set equal to the gravitational force at point C.  My question is, shouldn't the grav. force be 2mg and not mg because the blocks are now stuck together at point c?  I was also wondering if this review had been reviewed over the summer.  Thanks!

Pam - you are absolutely correct (and I assume you meant the centripetal force at point C).  It should be 2m, but fortunately for the solution, the mass cancels out anyway. And on the second line of the review, it is also missing a 2m, but the answer is correct.  John