Background: This law is sometimes paraphrased as “For every action, there is an equal and opposite reaction.” A very important point to remember is that the two forces are on different objects—never on the same object. It is frequently the case that one of the objects moves as a result of the force applied but the motion of the other object in the opposite direction is not apparent. Consider the situation where an ice skater is standing at the edge of the skating rink holding on to the side rail. If the skater exerts a force on the rail, the rail is held in place with tremendous friction and therefore, will not move in any noticeable way. The skater, on the other hand, had little friction with the ice, and therefore will be accelerated in the direction opposite of her original push. This is the process people use to jump up into the air. The person's feet exert force on the ground and the ground exerts an equal and opposite force on the person's feet. The force on the feet is sufficient to raise the person off the ground. The force on the ground has little effect because the Earth is so large. One of the accelerations is visible but the other is not visible.

Situation: Mike had spent the morning fishing and decided to head home. When he got to the dock he forgot to tie his boat to the dock before stepping off of it.

Question: What is exerting a force on the boat?

Situation: Mike had spent the morning fishing and decided to head home. When he got to the dock he forgot to tie his boat to the dock before stepping off of it.

Question: What is exerting a force on Mike?

Situation: Mike had spent the morning fishing and decided to head home. When he got to the dock he forgot to tie his boat to the dock before stepping off of it.

Question: Will the boat move towards or away from Mike?

Situation: Mike had spent the morning fishing and decided to head home. When he got to the dock he forgot to tie his boat to the dock before stepping off of it.

Question: Will Mike move towards or away from the boat?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: When Matt pushed off the boat did the boat move or stay stationary?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: Did the boat move in the same direction as Matt or away from him?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: Was the force on the boat less than or equal to the force on Matt?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: Was the force on Matt less than or equal to the force on the boat?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: What exerted force on the boat?

Situation: Matt had been fishing in his boat all morning and decided it was time to go for a swim. He stood on the edge of the boat and dived into the water. As he pushed of the boat he went forward into the water.

Question: Was the a lot or little friction with the water?