| A | B |
|---|
| Net force | The combination of all the forces acting on an object. |
| Balanced Forces | When equal forces are acting on an object in opposite directions. The net force is zero. Balanced forces do not change the object’s motion; remains at rest or at constant speed. |
| Unbalanced forces | When the net force acting on an object is not zero resulting in a change in motion. Unbalanced forces can cause an object to start moving, stop moving or change direction. |
| Newton | The unit for force in the SI system. Measured using a spring scale. |
| Projectile | An object that is thrown. |
| Momentum | The Product of an object’s mass and velocity. Momentum = Mass x Velocity |
| Law of Conservation of Momentum | States that when there are no outside forces the total momentum of objects that interact does not change. ex. if no gravity and no air resistance the Newton’s cradle would never stop moving. |
| Air resistance | The fluid friction experienced by objects moving through the air. When objects fall, air resistance pushes up. The faster the speed, the more air resistance. |
| Terminal velocity | The greatest velocity a falling object can achieve. When the force of air resistance pushing up balances with the force of gravity pulling down. |
| Free fall | The motion of an object when the only force acting on it is gravity. |
| Average Speed | Overall rate of speed at which an object moves. The total distance divided by the total time. |
| Instantaneous speed | The speed of an object in one instant of time. |
