An 18-m-long steel wire of 5-mm diameter is to be used in themanufacture of a prestressed concrete beam. It is observed thatthe wire stretches 45 mm when a tensile force P is applied. Knowingthat E 5 200 GPa, determine (a) the magnitude of the forceP, (b) the corresponding normal stress in the wire.

Physics 2 for Engineering Week 10 Sources of Magnetic Field 2 B = μ 0 4π (q v x r) / r -7 μ0= 4 π x 10 Magnetic field due to a straight current carrying conductor at a point P along an axis perpendicular to length B = μ 0 / 2π x for a long wire a>>x Magnetic field of a wire 2 2 B = (μ 0 / 4π) (2a / x √(x +a )) Force between parallel conductors F’ = I’ L’ x B F’ / L’ = μ0I I’ / 2πr Field due to I, B = μ 0 / 2πr Lorentz Force Fm = q v x B = q v B sin θ = I L B sin θ τ = d x F = r m g Magnetic field on the axis of a circular current loop B = μ I a / 2(x + a ) 2 3/2 0 For x <