Answer:
W = 49000 J
Explanation:
Given that,
Length of the cable, l = 50 m
Density of the cable, [tex]d=4\ kg/m[/tex]
The force acting on the cable is variable and it is equal to,
[tex]F=4l\ g[/tex]
Let W is the work is needed to pull the whole cable to the top of the building. It is given by :
[tex]W=\int\limits^{50}_0 {4lg\ dl}[/tex]
[tex]W=39.2\int\limits^{50}_0 {l.dl}[/tex]
[tex]W=\dfrac{39.2l^2}{2}|_0^{50}[/tex]
W = 49000 J
So, the work needed to pull the whole cable to the top of the building is 49000 J. Hence, this is the required solution.
