Newton’s Third Law of Motion
In any interaction between two objects, the forces exerted are always
equal in magnitude and opposite in direction.
“For every action there is an equal and opposite reaction”
Newton’s Third Law of Motion
In any interaction between two objects, the forces exerted are always
equal in magnitude and opposite in direction.
The Horse and the Wagon: A Newton’s Third Law Story
"Newton's Third Law says that if I pull on the wagon, the wagon exerts an equal and
opposite force on me,” says the Horse.
"If these two forces are equal and opposite, they will cancel, so that the net force is
zero, and I won’t move. So why should I even bother?”

FWagon pulling

FHorse pulling
backwards on the
Horse
forward on the
wagon
Earth
 Newton’s Third Law pairs do not cancel because they act on different objects!
But if I pull forward on the wagon, it will pull backwards on me, so how can I
move forward to market?

Fg of the Earth pulling

FN of the ground pushing
down on the Horse
upward on the Horse

F f of the surface pushing
forward on the Horse

Fg of the Horse

F f of the Horse pushing
backwards on the Surface
pulling up on
the Earth
Earth

FN of the Horse pushing
downward on the ground
 As long as the ground pushes forward harder on the Horse than the wagon pulls
backwards, the net force and therefore the resulting motion is forward!
The Tug-of-War

Fof the rope pulling

Fof me pulling
backwards
on the rope
forward on me

Fof the ground pushing
backwards on me

Fof me pushing
forward on the
ground
I must push harder on the ground than I pull on the rope, so that the ground
pushes back on me harder than the rope pulls forward! It’s all about how hard
you can push!