A rectangular metal block has length 15cm ,breadth 10cm and height 5cm. From this block a circular hole of diameter 7cm is drilled out find :
(a)the volume of the remaining solid
(b)the surface area of remaining solid
(i) the length , breadth and height of the metal block is 15 cm , 10 cm and 5 cm respectively.
therefore the volume of the rectangular block is 15*10*5=750 cubic cm
the diameter of the circular hole is 7 cm.
therefore the radius of the circular hole is 7/2=3.5 cm
the height of the circular hole will be equal to the height of the rectangular block i.e. 5 cm
the volume of the circular hole =
the volume of the remaining solid = volume of the rectangular block - volume of the circular hole
=750-192.5
=557.5 cubic cm
(ii)
the total surface area of the remaining solid
= surface area of the rectangular block - 2 *area of the circle of the hole + area of the curved surface of the hole (cylinder)
= [where l , b and h are the length , breadth and height of the rectangular block and r is the radius of the circular hole.
hope this helps you.
cheers!!