Please Help Me with Physics?

Question

I would appreciate any helpful input on this physics problem. I am really confused on this one. Thanks for any help :)

A high-speed lifting mechanism suppports a 815 kg object with a steel cable 28.0 m long and 4.00 cm2 in cross-sectional area.

a) Determine the elongation of the cable (in mm).

b) By what additional amount does the cable increase in length if the object is accelerated upward at a rate of 2.7 m/s2 (in mm)?

c) What is the greatest mass that can be accelerated upward at 2.7 m/s2 if the stress in the cable is not to exceed the elastic limit of the cable, 2.2 x 10 to the 8th power Pa (in kg)?

Answer 1

I expect that you have the data on stretch as a result of tension.
a) The object is just at rest. Tension, T = W = m*g.

b) T = W + m*a

c) Tmax = W + m*a