Newton’s Laws of Motion ROCKET SCIENCE Newton’s Laws of Motion

Newton’s First Law When a rocket lifts off it is because thrust exceeds the weight that keeps it in place. This reflects Newton's First Law of Motion, which states that an object at rest will stay at rest as long as no unbalanced force is applied. When a rocket reaches space, atmospheric drag (friction) is greatly reduced or eliminated. No additional rocket thrust will be needed. Its inertia will cause it to continue to travel outward.

Newton’s Second Law Two forces act on a rocket being launched. One is weight, the force generated by the gravitational attraction of Earth on the rocket. The other is thrust, the force that moves the rocket. Newton's Second Law of Motion applies here, as force (thrust) = mass × acceleration. This formula can also be used to determine the rate at which a rocket accelerates, because acceleration = force/mass.

Newton’s Third Law The movement of the high-speed exhaust in one direction propels the rocket in the opposite direction. This is Newton's Third Law of Motion in action; for every action there is an equal and opposite reaction. Drag is the rocket's resistance to motion caused by the rocket's movement through air. The nose cones of rockets are streamlined to help reduce drag.

Rocket Stability Rockets must be stable in flight — they must be able to fly in a smooth, predictable direction. Fins help stabilize the rocket when air is present. They are lightweight extensions attached to the exterior of the model rocket. They streamline the flow of air and provide a large surface area and help to keep the center of pressure behind the center of mass of the rocket.