The correct option is C 48 N
Given: mass of object m=36 kg, time, t=6 s, final velocity, v=4 ms−1 and inital velocity u=12 ms−1.
Let the acceleration of the body be a and the magnitude of force be F.
Using the first equation of motion.
v=u+at⇒a=v−ut=4−126==1.34 ms−2
Using Newton's second law,
F=ma=36×1.34=48 N
Thus, the magnitude of force is 48 N