Ken Hunnewell's physics class has been busy and fully engaged in the investigation of Newton’s third law of motion by building and launching model rockets. The law states that for “every action there is an equal and opposite reaction”. The action in the case of the rocket is the ejection of hot gas at high velocity from one end of the solid rocket engine when it ignites. The reaction is the rocket surges upward at a high speed. Students use their knowledge of force, acceleration and kinematics to predict the maximum height the rocket will achieve.
The students constructed a standard Estes model rocket (the “Alpha”). This imbues a sense of ownership and furthers student buy in. The students then calculate the flight profile using the Estes engine designation (A8-3) and the information in the Estes handbook as well as their knowledge of physics. No instructor guidance is given. The students are to reason out the flight profile by themselves in small groups.
The rockets are then launched and the maximum angle of elevation is measured by an altitude tracking device at the moment the parachute is deployed. Using this measurement and the distance from the launcher, the students calculate the actual height and compare it to their predicted values. Students are then asked to compare the predicted flight profile versus the actual flight profile and then brainstorm reasons for any possible variances.