A racecar rounds a curve at a perfectly constant speed. Why is it still considered to be accelerating?
ABecause the direction of its velocity is changing even though its speed is not
BBecause its speed is secretly changing even though the driver cannot feel it
CBecause friction from the tires always counts as acceleration
DIt is not accelerating, since acceleration requires a change in speed
Answer & Solution
Correct answer: A. Because the direction of its velocity is changing even though its speed is not
1. Velocity carries both a magnitude and a direction.
2. Going around a curve continuously changes the direction of the velocity vector.
3. A change in velocity of any kind, even direction alone, counts as an acceleration.
_Source: OpenStax Physics (CC BY 4.0), Ch 3 "Acceleration", section 3.1 Acceleration_
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