A particle covers two equal distances with speeds v and kv, where k > 0. Its average speed is:
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A particle covers two equal distances with speeds v and kv, where k > 0. Its average speed is:

G1 Physics · Accepted Answer

For equal distances, average speed is the harmonic mean: average speed = 2v₁v₂/(v₁+v₂). With v₁=v and v₂=kv, average speed = 2(v)(kv)/(v+kv) = 2kv/(k+1).