here we have to calculate the time taken by a Racehorse to cover a distance of 400 metre
as per the question the speed of the horse is 20 m/s
hence we have speed[V] = 20 m/s
the distance covered [S]=400 m
the relation between distance,time and the speed is given as


=

=20 second
hence the time taken by the horse is 20 second [ans]