Question

- A golf ball has a diameter of 4.1 cm and the surface
has 150 dimples of radius 2 mm. Calculate the total
surface area which is exposed to the surroundings.
(Assume the dimples' are hemispherical.)​

Answer 1

Answer:

area of circle =pi radius^2

then 1 cm is 10 mm then

4.1 cm is 41mm

after this we have to add 41mm and 2 mm

then it becomes 43mm

area=22/7×4.3×4.3

58.0880481649. hope it helps u. please mark my answer as brainliest

Answer 2

Answer:

Solution:-

Diameter of the ball = 4.1 cm 

Then, radius = 4.1/2 = 2.05 cm

Now, surface area of the ball without dimples = 4πr²

= 4*π*2.05*2.05

= 16.81 sq cm

It is given that the shape of dimples is hemispherical and radius of each dimple = 2 mm or 0.2 cm

Area of each dimple = 2πr²

2*π*0.2*0.2

= 0.08π sq cm

Area of 150 dimples = 150*0.08π

= 12π sq cm

Area of flat surface to removed to make one dimple = πr²

= π*0.2*0.2

= 0.04π sq cm

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

= 6π sq cm

Now,

total surface area of golf ball exposed to surroundings = Surface area of golf ball without dimples +

Area of 150 dimples - Area of flat surface removed to make 150 dimples

= 16.81π + 12π - 6π

= 28.81π - 6π

= 22.81π

= 22.81*3.14

= 71.62 sq cm

Answer.