Answer:
  Force required to accelerate = 794.44 N
Step-by-step explanation:
 Force required = Mass of horse x Acceleration of horse
 Mass of horse and rider, m= 572 kg
 Acceleration of horse and rider, a = 5 kph per second 
 

 Force required = ma
 = 572 x 1.39 = 794.44 N
 Force required to accelerate = 794.44 N