I need to know the correct answer please ?

675 Pa.

Explanation:

F = 5+2cos(15t) kN

Area (a) = 8*10-3 m2

Now at t =4 sec

            F= 5+2cos(60)

             = 5+2*0.5

              = 6  kN

Now ,force efficiency is 90%.

Hence,the effectively transmitted force,

            Fe = 0.90*6

                = 5.4 kN

Hence,pressure is given as,

            P = Fe/a

                = 5.4*10^3/(8 *10^-3))

              P = 675 Paanswer

the amount of current in the coil