Question

6. A medicine capsule is in the shape of a
cylinder with two hemispheres stuck to each
of its ends (see Fig. 13.10). The length of
the entire capsule is 14 mm and the diameter
of the capsule is 5 mm. Find its surface area.​

Answer 1

Answer:

surface area 219,8mm²

Scylinder = L*h

because diameter 5mm

h cylinder = 14-5 = 9mm

L = Pi*D

L = 3,14*5=15,7mm

Scylinder = 15,7*9 = 141,3 mm²

2 hemispheres = 1 sphere

Ssphere=4* Pi*R²

R=D/2   R=5/2  R=2,5mm

Ssphere=4* 3,14*2,5*2,5

Ssphere=78,5mm²

Scapsule = Scylinder+Ssphere

Scapsule = 141,3+78,5

Scapsule = 219,8mm²

Answer 2

Answer:   S = 70$\pi$ = 219.8 $mm^{2}$;

S = S1 + S2 +S3;

S1 + S3 = $4\pi R^{2} ;$   surface of a sphere (2 hemispheres = 1 sphere)

S2 = $2\pi Rh$;           lateral surface of the cylinder;

R = 5 / 2 = 2.5 mm;

h = 14 - 2 * 2.5 = 9 mm;

S = 4$\pi$*2.5*2.5 + 2$\pi$*2.5*9 = 25$\pi$ + 45$\pi$ = 70$\pi$ = 219.8 $mm^{2}$.