A truck is pulling a car out of a ditch by means fo a steel cable that is `9.1m` long and has a radius of `5mm`. When the car just beings to move, the tension in the cable is `800 N`. If Young's modulus for steel is `2xx10^(11) N//m^(2)` then the strecth in the cable is (neraly)

Explanation

Here, `l = 9.1 m, r = 5 mm = 5xx 10^(-3)m , F = 800 N, Delta l = ?, Y = 2xx10^(11) N//m^2`
`Y = (Fl)/(pi r^2 Delta l) or Delta l = (Fl)/(pr r^2 Y)`
`:. Delta l = (800 xx 9.1)/((22//7) xx (5xx10^(-3))^2 xx (2xx10^(11))) = 4.64 xx 10^(-4) m ~~ 5xx10^(-4)m`