Question

If action is always equal to reaction then explain how a horse can pull is called

Answer 1

According Newton's Third Law of motion , For every action force there is an equal and opposite reaction force.
Action = -Reaction
Action force is exerted by horse on car when horse pulls the carts.
if we have a look at forces acting on horses, horse will exert action force on the ground by its feel where as reaction force exerted by ground on horse makes the horse move forward.
note;
Here frictional force plays a very important role.
frictional force should be more than action force.
Let F be the force applied by horse.
f = frictional force
fnet = F - f
where from Second law , Fnet = ma so, ma = F - f
So acceleration will be produced.
Which makes the cart move.

Answer 2

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The horse pushes the ground in the backward direction in reaction of this, the horse moves forward and cart moves along with the horse in the forward direction . In this case , when the horse tries to pulls the cart in the forward direction , then card pulls the horse in the backward direction, but because of the unbalanced force applied by the horse, cart moves in forward direction.✅✅