# Physics Paper

1688 Words7 Pages
January 8, 2014 Honors Physics Model Rocket Project Paper The purpose of this is to explain the impulse-momentum theorem through launching rockets. The impulse-momentum theorem says that any impulse acting on a system changes the system’s momentum. Model rockets work by using a propellant that is forced by igniting it through a delay charge, then an ejection charge. This reaction will force the model rocket to soar through the air. My hypothesis for this project is that our rocket will go 100 feet in the air (apogee) and we will easily recover it. I predict the total time to apogee will be 10 seconds and the time of thrust will be 5 seconds. Sir Isaac Newton’s first law states that every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force. This is normally taken as the definition of inertia. The key point here is that if there is no net force acting on an object (if all the external forces cancel each other out) then the object will maintain a constant velocity. If that velocity is zero, then the object remains at rest. And if an additional external force is applied, the velocity will change because of the force. A model rocket lifting off from the launch pad is a good example of this principle. Just prior to engine ignition, the velocity of the rocket is zero and the rocket is at rest. If the rocket is sitting on its fins, the weight of the rocket is balanced by the re-action of the earth to the weight as described by Newton's third law of motion. There is no net force on the object, and the rocket would remain at rest indefinitely. When the engine is ignited, the thrust of the engine creates an additional force opposed to the weight. As long as the thrust is less than the weight, the combination of the thrust and the re-action force through the fins balance the weight and