Refer to Figure \(12.18(\mathrm{c}) .\) A lintel of prestressed reinforced
concrete is \(1.50 \mathrm{m}\) long. The cross-sectional area of the concrete
is \(50.0 \mathrm{cm}^{2} .\) The concrete encloses one steel reinforcing rod
with cross-sectional area \(1.50 \mathrm{cm}^{2} .\) The rod joins two strong
end plates. Young's modulus for the concrete is \(30.0 \times 10^{9} \mathrm{N}
/ \mathrm{m}^{2} .\) After the concrete cures and the original tension \(T_{1}\)
in the rod is released, the concrete is to be under compressive stress \(8.00
\times 10^{6} \mathrm{N} / \mathrm{m}^{2} .\) (a) By what distance will the rod
compress the concrete when the original tension in the rod is released? (b)
The rod will still be under what tension \(T_{2} ?\) (c) The rod will then be
how much longer than its unstressed length? (d) When the concrete was poured,
the rod should have been stretched by what extension distance from its
unstressed length?
(e) Find the required original tension \(T_{1}\) in the rod.