Multiple choice

During its motion along a $30 km$ path, a car takes $10 min$ to cover first $10 km$, $15 min$ to cover next $10 km$ and $20 min$ to cover the rest of the distance. So, the body moves with:

  1. constant speed

  2. acceleration

  3. retardation

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The speeds for the three segments are 1 km/min, 0.66 km/min, and 0.5 km/min respectively. Since the speed is decreasing over time, the car is undergoing retardation.

AI explanation

Calculate the speed for each interval to determine the motion characteristics of the car. The speed during the first 10 km is 10 km / (10/60) hr = 60 km/hr. The speed during the next 10 km is 10 km / (15/60) hr = 40 km/hr, and the speed for the final 10 km is 10 km / (20/60) hr = 30 km/hr. Since the equal distances are covered in increasing amounts of time, the speed is continuously decreasing, indicating the body moves with retardation.

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