Question

A tow truck is pulling a car out of a ditch by means of a steel cable that is 10.2 m long and has a radius of 0.50 cm. When the car just begins to move, the tension in the cable is 870 N. How much has the cable stretched?

COnstant for Steel cable Y=2.0e11

Answer 1

Please mention the units when there is a mix of units. (10.2 m, 0.5 cm, 2.0e11 Pascal, etc.)

Also, note that cables do not have a solid cross section. Lack of better information, we will assume the section to be solid. The actual deformation will be higher than calculated.

Modulus of elasticity, E = 2.0e11 pascals
tension, T=870 N
length, L=10.2 m
radius of cable, r = 0.005 m.
Area of cable, A = πr²
deformation, ΔL
=(stress/Mod.Elasticity)*L
=(T/A / E )*L m