Question

A cube of metal of 2.5 cm edge is melted and cast in to rectangular solid whose base is 1.25 cm by 0.25 cm .Assuming no loss in melting find the height of the solid . Also find the gain in the surface area.

Answer 1

Correct Answer - 1000 sq.cm
Volume of the cube =`("edge"^(3))=(2.5^(3))` cu cm
Area of the base of rectangular solid =12.5`xx`0.25 sq.cm
Height of solid =`("volume")/("area of base")=(2.5^(3))/(1.25xx0.25)`=50cm
surface area of the cube =`6xx("edge")^(2)=6xx(2.5)^(2)=37.5` sq.cm
Surface area of the solid =2(lb+bh+hl)=`2(50xx1.25+1.25xx0.25+50xx0.25)`
Gain in surface area =150.625-37.50=113.125 sq.cm