FB apps(3):for making only...

2011-03-30 6:09 am

A sculpture is cut from a wooden cylinder as shown in the figure.The sculpture is made up of a circular cone at the top,a cylinder in the middle which is height 5.5cm&a hemisphere at the bottom.It's found that 25% of the material is removed from the cylinder in order to make the sculpture.If the cone's ratio is 1.5cm,
(A)find the value of x which is the height of the cone
(B)If the cost of polishing a wooden object is $0.3 per cm^2, find the cost of polishing the whole surface of the sculpture.

回答 (1)

MythalyZer

2011-04-07 5:09 am

✔ 最佳答案

I don't know whatever the answer is correct or not....Just try.

(A)find the value of x which is the height ofthe coneSol: Thetotal volume=(1/3)*1.5^2πx+1.5^2π*5.5+(4/3)(1/2)*1.5^3*π=61.084+7.4022x (corr. To5sig-fig)Set up equation.1.5^2π*5.5=(1/4)(61.084+7.4022x) x=94.424/7.4022 =12.756 cm(corr. To 5 sig-fig)(B)If the cost of polishing a wooden objectis $0.3 per cm^2, find the cost of polishing the whole surface of thesculpture.Sol:The total surface area= √(12.756^2+1.5^2) * 2π*1.5+1.5*2π*5.5+4π*1.5^2=201.16cm^2(corr.to 5sig-fig)The cost=201.16*0.3=$60.3(corr. to 3sig-fig)

參考: my brain

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