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Newton’s third law of motion states that “for every action there is an equal but opposite reaction.” An example of action and reaction is two basket balls. If you roll one ball at the other ball, when it hits the other ball it will exert a force on the still one. In return, the still one exerted an equal, but opposite, force on the rolling ball. This reaction force caused the ball you rolled to slow down. Before, your friend drove you off the ice by jamming the gas pedal. With the wheels spinning at full speed, you slowly got back on the pavement. Once the tires reached the pavement, there was enough friction for the wheels could grip the road, so you sped off at full speed. Your friend, still panicking over the ice, drove right into the back of his old truck. If you knew he was this bad with directions, you might not have let him drive. The force of the car hitting the truck was the action force. Which sure enough was met with a reaction force! This reaction force brought your car to an immediate stop. I explained before that equal forces acting in opposite directions create a net force of zero. Action and reaction forces are equal forces acting in opposite directions. The reason they don’t cancel each other out is they are acting on different objects. When the ball you rolled hits the still one, the force of the moving ball acts on the still ball. The reaction force acts on the one you rolled. The two forces can’t be added together because they are acting on different objects.
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Space in the Spotlight
Novi Meadows Elementary 2002
All pictures courtesy of NASA unless otherwise noted |
