1. Action force: This is the force that the kangaroo's legs exert on the ground when it jumps. This force is responsible for propelling the kangaroo into the air.
2. Reaction force: This is the force that the ground exerts on the kangaroo in response to the action force. This force is equal in magnitude but opposite in direction to the action force.
The reaction force is what allows the kangaroo to jump off the ground and propel itself into the air. Without this force, the kangaroo would simply sink into the ground when it tried to jump.
The action and reaction forces are both examples of Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. This law is fundamental to our understanding of how forces work in the world around us.