On an object of mass 1 kg moving along x-axis with constant speed 8 m/s a constant force 2 N is applied in positive y-direction. Find its speed after 4 seconds

v ( x - axis) - no change since there is no external force applied

v (y - axis)

Initial v = 0 m/s
t = 4 sec
a = Fy/m = 2m/s^2

Vy = 0 + 2 x 4 = 8 m/s

V = (Vx^2 + Vy^2)^1/2
= 8.2^1/2