A coin sitting on a bus seat slides forward when the bus brakes suddenly. This is best explained by:
AAction and reaction pairs, since the road pushes the bus backward
BNewton's first law, the coin tends to keep moving in a straight line
CConservation of momentum, since total momentum of the bus stays fixed
DNewton's second law, since the brakes apply a force on the coin directly
Answer & Solution
Correct answer: B. Newton's first law, the coin tends to keep moving in a straight line
The coin has no external horizontal force on it; by the first law, it tends to keep moving forward while the bus floor decelerates.
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