
In frame of block of mass M moving with acceleration a.

m1a – T = 2m1
10a – T = 20 …(i)

T – m2g = 2m2
T – 200 = 40
T = 240 …(ii)
From equation 1 and 2
10a = 260
or, a = 26 m/s2
for block
F = (M + m2)a
F= 120 × 26
F= 3120 N
So, the correct option is (C): 3120 N
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field \( B \) exists into the page. The bar starts to move from the vertex at time \( t = 0 \) with a constant velocity. If the induced EMF is \( E \propto t^n \), then the value of \( n \) is _____. 
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