Newton's 3rd Law EX 1

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The diagram shows all the action-reaction pairs:

TOP

Force Action-reaction pair
Gravity FG EP
The gravitational force exerted by the Earth on the puck
FG PE
the gravitational force exerted by the puck on the Earth
Normal force FN IP
The normal force exerted by the ice on the puck
FN PI
The normal force exerted by the puck on the ice
Force of friction Ff IP
The force of friction exerted by the ice on the puck
Ff PI
The force of friction exerted by the puck on the ice


The magnitude of FG EP is 3 N (0.3 kg x 10 N/kg) and the magnitude of FG PE is also 3 N.

The magnitude of FN PI is 3 N and the magnitude of FN IP is also 3 N.

The magnitude of Ff PI is 0.06 N and the magnitude of Ff IP is also 0.06 N.

Important note: Even though FG EP and FN IP are equal and opposite forces, they are not an action-reaction pair!