SURFACE AREAS
AND VOLUMES
Sol.
Radius (r) =
2
5
= 2.5 mm
Length of the cylinder (h) =
14
– 2.5
– 2.5
= 9mm
CSA of the cylinder (S1) =
2 π r h
=
2 × π
× 2.5
× 9
=
45π mm2
CSA of 2 hemispheres (S2) =
2 × 2πr2
=
2 × 2 × π
× (2.5)2
=
25π mm2
The entire capsule is made up of a cylinder and two hemispheres
5 mm
What is the formula to find curved surface area of cylinder ?
What is the formula to find curved surface area of hemisphere ?
Total surface area of capsule =
14 mm
Q. A medicine capsule is in the shape of a cylinder with two
hemispheres stuck to each of its ends. The length of the entire
capsule is 14mm and the diameter of the capsule is 5 mm.
Find its surface area.
2.5 mm
2.5 mm
9 mm
∴
CSA of the cylinder (S1)
CSA of 2 hemispheres (S2)
∴
Let us find the height of the cylinder
We know that,
Radius =
In Hemisphere,
Height
Diameter =
5 mm
2
d
=
∴
?
h
CSA of cylinder (S1) +
2 CSA of hemisphere(S2)
2 π r h
2 π r2
?
✔
?
?
✔
✔
∴
Sol.
TSA of the capsule =
S1 + S2
=
45π
+
25π
=
70π
=
70
7
×
22
10
=
220 mm2
Surface area of the capsule is 220 mm2
5 mm
14 mm
2.5 mm
2.5 mm
S2 = 25π
S1 = 45π
∴
Total surface area of capsule =
Q. A medicine capsule is in the shape of a cylinder with two
hemispheres stuck to each of its ends. The length of the entire
capsule is 14mm and the diameter of the capsule is 5 mm.
Find its surface area.
CSA of cylinder (S1) +
2 CSA of hemisphere(S2)
2 π r h
2 π r2