A wire that is highly insulated has a radius of 2.1 mm and a current
of 6 Agoes through it. The material used in insulation has thickness
of 2.1 mm with a thermal conductivity of 0.2 W/Km. the material used
in constructing the wire has a resistivity of 4.2 × 10^(−7) Ωm. assume the
the materials reach steady state. Find the difference in temperature
between the outer suface and inner surface.
A man and a woman have 3 boys and 3 girls.
(i) in how many ways will they sit in a row such that
the 3 boys and 3 girls are inbetween the man and woman.
(ii) Say the man decides of the 3 boys and 3 girls he has 2
of the kids should help him out in a project,
in how many ways can this be done, if heyoungest boy and oldest
girl can′t join.
let a,b,c be positive real numbers such
that ab+bc+ac=3
prove the inquality
((a(b^2 +c^2 ))/(a^2 +bc))+((b(c^2 +a^2 ))/(b^2 +ac))+((c(b^2 +a^2 ))/(c^2 +ab))≥3