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Question
According to the third law of motion, when we push on an object, the object pushes back on us with an equal and opposite force. If the object is a massive truck parked along the roadside, it will probably not move. A student justifies this by answering that the two opposite and equal forces cancel each other. Comment on this logic and explain why the truck does not move.
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Solution
- The truck has a big bulk. As a result, the truck's static friction with the road is extremely high.
- To move the car, one must exert more force than static friction. As a result, when someone pushes the vehicle and it does not move, the imparted force in one direction is balanced by an equivalent amount of frictional force operating in the opposing direction.
- As a result, moving the vehicle requires a significant amount of imbalanced force.
- As a result, the student is correct in claiming that the two opposite and equal concepts cancel each other out.
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