[" 24.A block of mass "m" is placed on a surface with a vertical "],[" cross section given by "y=(x^(3))/(6)" .If the coefficient of friction "],[" is "0.5" ,the maximum height above the ground at which the "],[" block can be placed without slipping is "],[[" (a) "(1)/(2)m," (b) "(1)/(6)m],[" (c) "(2)/(3)m," (d) "(1)/(3)m]]