# Physics question regarding Young's modulus.



## AznFlacco52 (Feb 14, 2011)

You want to use a steel cable to tow your car (m = 2120 kg). The cable is solid steel with a diameter of 1.1 cm and a length of 12 m. If you are pulling the car such that its acceleration is 1.4 m/s2, how much will the cable stretch?

Here is my work:
F= 2120 * 1.4 = 2968
A= pi * (.011/2)^2
Y= 2 * 10^11
L0 = 12

Change in L = (2968*12)/((2*10^11)*(9.5033*10^11))
= .00187

Apparently this is not the answer even though i'm pretty sure the math is correct. Can someone tell me if I did this right?


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## BusinessMan (Apr 21, 2011)

AznFlacco52 said:


> You want to use a steel cable to tow your car (m = 2120 kg). The cable is solid steel with a diameter of 1.1 cm and a length of 12 m. If you are pulling the car such that its acceleration is 1.4 m/s2, how much will the cable stretch?
> 
> Here is my work:
> F= 2120 * 1.4 = 2968
> ...


I just did it myself and got the exact same answer as you.

I used:

Lc = (F*L) / (A*Y)

In my years of engineering the book had the wrong answer on more than one occasion.


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