Answer:
Force required to accelerate = 794.44 N
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
Answer:
Option (b) is correct.
Explanation:
The motion under the influence of gravity is called projectile motion.
The acceleration due to gravity is constant through out the motion and it is always acting downwards.
When an athlete jumps and follow the projectile path, it always have the same horizontal velocity as there is no acceleration in the horizontal direction.
Also he has the vertical acceleration constant which is equal to the acceleration due to gravity and acts towards the center of earth.
Option (b) is correct.