Every action force has an opposite and equal reaction force. Determine which of these are action/reaction pairs. Check all that apply.

The action-reaction pairs according to Newton's Third Law of Motion are:

1. A girl leans against a wall and the wall pushes on the girl. ✔️

   • Action: The girl exerts a force on the wall.
   • Reaction: The wall exerts an equal and opposite force on the girl.

2. A baseball hits a glove and the glove pushes on the ball. ✔️

   • Action: The baseball exerts a force on the glove.
   • Reaction: The glove exerts an equal and opposite force on the baseball.

3. A boy pushes on a door and the door swings open. ✖️

   • This scenario does not clearly describe a direct action-reaction pair. While the boy exerts a force on the door, without specifying the reaction, it cannot be identified as a direct action-reaction pair.

4. A soccer player kicks a ball and then another soccer player kicks the same ball. ✖️

   • This scenario involves two separate actions and does not form a direct action-reaction pair. The first soccer player kicking the ball is one action, and the second soccer player's kick is another independent action.

5. A cat rubs up against a tree and the tree pushes against the cat. ✔️

   • Action: The cat exerts a force on the tree.
   • Reaction: The tree exerts an equal and opposite force on the cat.

6. A student pushes another student standing in a line, and that student falls into the next student. ✖️

   • This scenario describes a chain of events and does not detail a direct action-reaction pair. While the push is an action, the reaction of the second student falling into the next does not represent a clear action-reaction pair between the first student and the second student.

In conclusion, the valid action/reaction pairs from the list are the first, second, and fifth options.