A very light wire i s used to hang a series of 8.0 - kg bricks. This wire will b

Question

A very light wire i s used to hang a series of 8.0 - kg bricks. This wire will break if the tension in it exceeds 450 N. The bricks are hung one below the other from a hook in the ceiling using this wire, as shown in the figure.

(a) How many whole bricks can be hung without breaking the wire?

(b) If you add one more brick to the number found in part (a), which string will break?

I know the answer to (a) is 5 and (b) is the top wire... I hope the question explains the figure well enough cuz I do not know how to paste the figure into here...

If you can, please include all the steps with reasoning if needed. thank you

Explanation / Answer

a. Wt of each brick= mg=8.0*9.8=78.4 N

                Let n bricks be hung.

                wt of n bricks< max tension

                78.4n<450

                n<5.74, thus max brick should be 5 as it should be whole no.

b. The wire at the top will breakas it will bear the load of all 6 bricks.

The wire below the top wire will have wt on 1 less brick and the wire below it will have even 1 more less. Thus the top wire will have max stress and break

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