Calculating Force in System S' Using Lorentz Transformation

[mntb]

Consider an object of mass m at rest in S acted upon by a force F with components Fx and Fy. Sys tem S' moves with instantaneousvelocity v in teh x direction. Defining the force with F=d/dt (gamma mv), and using the Lorentz velocity transformation, show that a0 F'x=Fx,b0 F'y=Fy/gamma
I show my work and problem in word doc: problem with calculus, cause it couldn't show up properly here
second question, is it okay to see v/c^2 as zero in this case, then F'y would be equal to Fy/gamma, I mean to ignore v/c^2?

 

[malawi_glenn]

For relativtistic momentum px = gamma(u)*m*ux and py = gamma(u)*m*uy where u^2 = ux^2 + uy^2 is the particle speed in S