what force must be exerted on an electron to move it from a state of rest to a speed of 3.5 x 10^7 m/s in a distance of 0.75 m?
V^2=Vo^2+2ax
3.5x10^7=2a(0.75)
3.5x10^7=1.50a
divide by 1.50 on both sides to get "a" by itself
a = 2.3x10^7 m/s^2
next use Newton's 2nd law F=ma
F=(9.1x10^-31)(2.3x10^7) *9.1x10^-31 is the mass of the electron)
your answer is F = -1.3x10^3 Newtons
Done.