Multiple choice

A car covers half of the distance with speed $60 km/hr $ and rest of the half with speed $ 30 km/hr $ . The average speed of the car is -

  1. $ 45 km/hr $
  2. $ 40 km/hr $
  3. $ 20.0 km/hr $
  4. $ 50 km/hr $
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed for equal distances is 2*v1*v2 / (v1+v2). Here, 2 * 60 * 30 / (60 + 30) = 3600 / 90 = 40 km/hr.

AI explanation

When equal distances are covered at two different speeds, the average speed is given by the harmonic mean formula: 2xy/(x+y). Substituting the given speeds of 60 km/hr and 30 km/hr, we calculate the average speed as (2 * 60 * 30) / (60 + 30) = 3600 / 90. This simplifies to 40 km/hr.

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