A golf ball has a diameter equal to 4.1cm. Its surface has 150 dimples each of radius 2mm. Calculate the total surface area which is exposed to the surroundings assuming that the dimples are hemispherical.
(Ans: 71.68)
Ans: SA of ball = 4π × ( 4.1/2 )2 = 16.8 π cm2
TSA exposed to surroundings
= SA of ball - 150 × π r2 + 150 × 2π r2
= 16.8 π + 150 π r2
= 71. 68 cm2