A car travels equal distance in the same direction with velocities 60km h-1, 20km h-1 and 10km h-1 respectively. The average velocity of the car over the whole journey of motion is:
Correct answer: D. 5 ms-1
- A. 8 ms-1
- B. 6 ms-1
- C. 7 ms-1
- D. 5 ms-1
Explanation
To determine the average velocity when a car travels equal distances at different speeds, use the harmonic mean formula for average velocity. Since the car travels equal distances with velocities of 60 km/h, 20 km/h, and 10 km/h, the average velocity is calculated as follows:The harmonic mean formula for velocities when distances are equal is given by: Average velocity = 3 / (1/60 + 1/20 + 1/10) km/h = 18 km/h. Converting 18 km/h to m/s, we get 5 m/s.Therefore, the correct answer is 5 m/s. The other options are incorrect as they result from incorrect calculations or interpretations of the average velocity formula for equal distances.
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