Science and Math For Technology
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- Newton’s first law of motion.
- Momentum
- Action and Reaction
Inertia and Momentum Inertia is the property of objects to resist a change in motion. For example, when an automobile stops fast, the people inside, resisting a change in motion, move forward. Inertia can be a big problem when we try to move a large object. A lot of energy is needed to start an automobile rolling. It takes less energy to keep the automobile rolling once it is moving. This concept of inertia is Newton’s first law of motion. 
Momentum is the measure of the impact of a moving body when it hits another body. Momentum is figured by multiplying the mass or amount of matter in a body times the velocity. For example, a large bowling ball travelling down an alley will have more momentum than a small bowling ball travelling at the same velocity. Effort is required to start a body in motion, and the same effort is needed to stop it.  
Action and Reaction Action and reaction form the basis of Newton’s third law of motion. This law states that forces always exist in pairs. When an object has a certain force in a given direction, some other body will receive an equal force in the opposite direction.   
Have you ever jumped from a boat to a dock? The initial force is you jumping to the dock. The boat moving away from the dock is the reactive force. We have all seen a hamster running nowhere on a wheel. The hamster exerts force by running forward. The reactive force turns the wheel in the opposite direction. Keep in mind that the initial force acts on one body and the reaction force acts on another body. Explain this concept in the three pictures above. 
You can make a balloon travel across the room by allowing the gases inside the balloon to escape. As the gases flow out, the balloon moves in the opposite direction. This is the same as the reactive force of a rocket engine. As the gases escape downward, the rocket moves in the opposite direction. As the gases escape downward, the rocket moves in the opposite direction, or upward.  
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