Answer:
Force required is 16 N.
Step-by-step explanation:
By Newton's second law of motion,
F = ma
where F is the force,m is mass and a is acceleration.
Given:
initial speed = u = 3 m/s.
final speed = v = 15 m/s
time taken = t = 3 s
acceleration = a =
![(v-u)/(t)=(15-3)/(3)=4\ ms^(-2)](https://img.qammunity.org/2020/formulas/physics/high-school/huebcf8h3jfmnayxflx4xjguurptoxumo1.png)
mass of the rock = 4 kg
Force = mass*acceleration = 4*4 = 16 N.