Answer:
Area is 0.08504[tex]ft^{2}[/tex] and [tex]2.6\times 10^{3}s[/tex] are needed for polishing
Explanation:
(a) ft is unit of F.P.S system whether mm is unit of M.K.S system.
According to unit conversion, [tex]1mm=0.00328ft[/tex]
So, [tex]1mm^{2}=(0.00328)^{2}ft^{2}=1.076\times 10^{-5}ft^{2}[/tex]
hence, [tex]7903mm^{2}=7903\times 1.076\times 10^{-5}ft^{2}=0.08504ft^{2}[/tex]
So, area of telescope lens is 0.08504[tex]ft^{2}[/tex]
(b)[tex]135mm^{2}[/tex] are polished in 45s
So, [tex]7903mm^{2}[/tex] are polished in [tex]\frac{45\times 7903}{135}s[/tex] or [tex]2.6\times 10^{3}s[/tex]
