Asked in Premeth — Coordination and Control, Vectors and EquilibriumModerate

Consider a car is travelling for one hour. In which of the following cases is the average velocity zero?

Correct answer: D. The car travels 30 km due west, then turns around and travels 30 km due east.

  • A. The car travels 20 km due east.
  • B. The car travels 60 km due east, then turns around and travels 40 km due west.
  • C. The car travels 70 km due east.
  • D. The car travels 30 km due west, then turns around and travels 30 km due east.

Explanation

We know that average velocity = total displacement/total time.The car travels 30 km due west, then turns around and travels 30 km due east.Since displacement is a vector quantity and needs direction.Let's assume that positive displacement is towards the west and negative displacement is towards the east.Therefore:Average Velocity = +30 + (-30)/1= 0/1= 0 km/hr.

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Displacement is the directed change in position, while velocity is the rate of change of displacement and includes both magnitude and direction. The topic connects position-time and velocity-time graphs with average and instantaneous values, and distinguishes displacement from distance and velocity from speed.

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