A cylinder 15 cm long and 9 cm in radius is

made of two different metals bonded end-to-
end to make a single bar. The densities are
4.3 g/cm3 and 6.3 g/cm3.
15 cm
9 cm radius
What length of the lighter-density part of
the bar is needed if the total mass is 21757 g?
Answer in units of cm.
0

1 answer

metal A length x
metal B length (15-x)

x(4.3)(pi r^2) + (15-x)(6.3)(pi r^2)
= 21757

4.3 x + 94.3 - 6.3 x = 21757/(81 pi)

2 x = 8.8

x = 4.4 cm