A 60⁢kg board that is 6 m m long is placed at the edge of a platform, with 4m of its length extending over the edge. The board is held in place by blocks of masses M1M1 and M2M2 placed with their centers of mass on either end. If M2=30kg M2=30kg , what is the minimum value of M1 needed to keep the board from falling off the platform?
30kg
50kg
60kg
70kg
90kg