Question:
A truck is pulling a car out of a ditch by means of a steel cable that is 9.1 m long and has a radius of 5 mm. When the car just begins to move, the tension in the cable is 800 N. How much has the cable stretched?
Solution:
Length of steel cable, l = 9.1 m
Radius, r = 5 mm
Tension on the cable = 800 N
Young’s modulus = Y = 2 × 1011 N/m2
Y = (F/A)/( ∆L/L)
∆L = 0.5 × 10-3 m