For example, think about one car rear-ending another car that is stopped at a red light. When two cars crash at a high enough speed, both cars are usually damaged (Figure 2). In this lesson plan, you will illustrate Newton's third law by crashing model cars that the students build themselves. For example, if you say "When you push on a wall, the wall pushes back on you," students might ask "How can a wall push if it can't move?" The lesson will help you address some of these misconceptions with students. It can be difficult to grasp how an inanimate object can push. Students may associate exerting a force with things that can move, such as a person pushing a box across the floor, or a snow plow pushing a pile of snow. Equal and opposite forces only cancel each other if they act on the same object. in Figure 1, the action force acts on the table, and the reaction force acts on the book). This is because the two forces act on different objects (e.g. For example, students might ask why the two equal and opposite forces don't just cancel each other out. This concept can be confusing for students, and several misconceptions exist. Action and reaction forces between a book and a table. Structures can be designed to serve particular functions by taking into account properties of different materials, and how materials can be shaped and used.įigure 1. Sometimes parts of different solutions can be combined to create a solution that is better than any of its predecessors. This lesson focuses on these aspects of NGSS Three Dimensional Learning: Science & Engineering Practicesĭevelop a model to generate data to test ideas about designed systems, including those representing inputs and outputs.įor any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in the opposite direction (Newton's third law).Ī solution needs to be tested, and then modified on the basis of the test results, in order to improve it. This lesson helps students prepare for these Next Generation Science Standards Performance Expectations:Īpply Newton's Third Law to design a solution to a problem involving the motion of two colliding objects.ĭevelop a model to generate data for iterative testing and modification of a proposed object, tool, or process such that an optimal design can be achieved. Apply knowledge of Newton's third law to explain what happens in a car crash.Use the engineering design process to iteratively design, build, and test a product.Combine Newton's third law of motion with engineering design in one fun lesson! Your students will learn about equal and opposite reaction forces as they design and build a bumper to protect a toy car during a crash.