1. Teacher Page IV. Force, Motion and Mechanical Energy B. Types and properties of Forces and Motion 7th grade assessment Science standards 1.4; 1.7; 2.1; 3.5; 3.7; 4.1 Students should know whenever an object exerts a force on another, an equal but opposite force is exerted back on it. View lesson before using with students --- sample questions and answers appear on mouse click.

2. Newton’s Third Law of Motion If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

3. In your journal use Newton’s third law to explain the forces when you run. When you run, you push the ground with your feet. The ground pushes back on your feet with an equal and opposite force. You go forward when you run because the ground is pushing you.

4. Can you use Newton’s third law to explain how a bird flies? A bird flies forward by exerting a force on the air with its wings. The air pushes back on those wings with an equal force that propels the bird forward.

5. Explain how a shark uses Newton’s third law to move through the water. The shark exerts a force on the water using its fins. At the same time, the water exerts an equal and opposite force on the shark, causing it to move.