Answer :
If he's coasting on a flat road, then there is no acceleration ...
his speed is constant and he's moving in a straight line.
No acceleration means the net force acting on him is zero.
Horizontal forces add to zero:
Nothing pushing him from behind.
Nothing pulling him from in front.
No horizontal forces.
Vertical forces add to zero:
Force of gravity pulling him down, equal to the weight of him plus the bike.
Equal normal force, pushing him up, exerted by the road.
his speed is constant and he's moving in a straight line.
No acceleration means the net force acting on him is zero.
Horizontal forces add to zero:
Nothing pushing him from behind.
Nothing pulling him from in front.
No horizontal forces.
Vertical forces add to zero:
Force of gravity pulling him down, equal to the weight of him plus the bike.
Equal normal force, pushing him up, exerted by the road.