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GED Physical Science
Lesson 5 Motion and Forces
Term | Definition |
---|---|
speed | the rate at which an object moves |
velocity | an object's speed in a particular direction |
acceleration | the rate at which velocity changes |
force | anything that tends to change the state of rest or motion of an object (pushing/pulling/gravity/friction, etc) |
laws of motion | three laws by which the planets and all other objects move when acted upon by a force (set down by Sir Isaac Newton, an English physicist and mathematician) |
law of inertia | Newton's first law of motion states that an object at rest will stay at rest until a force acts upon it, and an object in motion will stay in motion at a constant speed in a straight line until a force acts upon it |
momentum | related to the amount of energy that a moving object has, and it depends on the mass of the object and its velocity (all forces exist in pairs, and all forces are interactions between objects) |
law of motion (or acceleration) | Newton's second law states that the acceleration of an object depends on its mass and the force acting upon it; the greater the force, the greater the acceleration; the more massive the object, the more force it takes to accelerate it |
Newton's 3rd law | states that for every action, there is an equal and opposite reaction; this was used to derive the law of conservation of momentum |