Final answer:
Walking across a room involves applying Newton's third law of motion, where pushing backward against the ground results in an equal and opposite force from the ground, propelling you forward. The level of friction on different surfaces affects this interaction, and low friction surfaces like ice can make walking challenging.
Step-by-step explanation:
When you walk across a room, you are applying Newton's third law of motion which states that for every action, there is an equal and opposite reaction. As you push backward against the ground with your feet, the ground applies an equal and opposite force that pushes you forward, allowing you to move. This interaction involves contact forces where your feet exert a force on the floor, and in response, the floor exerts an equal and opposite force on your feet, propelling you forward. Walking on different surfaces like ice can be challenging because the friction force, which is also a contact force, becomes significantly lower, reducing the amount of push-back you receive from the ground and making it difficult to move without slipping.