Question

A golf ball has diameter equal to 4.1 cm. Its surface has 150 dimples each of radius 2 mm
Calculate total surface area which is exposed to the surroundings. (Assume that the dimples are all hemispherical)[π=22/7]​

Answer 1

Step-by-step explanation:

Surface area of the golf ball = 4×π×(4.12)2=16.81πcm2 .

Answer 2

Answer:

ANSWER

Diameter of golf ball=4.1㎝

Radius of golf ball=

2

4.1

=2.05㎝

Surface area of ball=4πr

2

=4π×(2.05)

2

=16.81π㎠

Radius of each dimple=2mm=0.2㎝

Area of 150 dimples=150×2πr

2

=150×2×π×(0.2)

2

=12π㎠

Area of flat surface removed to make 1 dimple=0.04π㎠

∴Area of flat surface removed to make 150 dimples=150×0.04π

=6π㎠

TSA of golf ball exposed to surroundings=16.81π+12π−6π

=22.81π=22.81×

7

22

=71.70㎠