Two rectangular blocks A and B are placed on a horizontal surface at a very small separation. The masses of the blocks are `m_(A) = 4` kg and `m_(B) = 5` kg. Coefficient of friction between the horizontal surface and both the blocks is `mu = 0.4`. Horizontal forces `F_(1)` and `F_(2)` are applied on the blocks as shown. Both the forces vary with time as `F_(1) = 15 + 0.5 t `
`F_(2) = 2t`
Where ‘t’ is time in second.
Plot the variation of friction force acting on the two blocks (`f_(A) "and" f_(B)`) vs time till the motion starts. Take rightward direction to be positive for B and leftward direction to be positive for`f_(A)`.

Answer

`(##IJA_PHY_V01_C03_E01_123_A01##)`