an object move 20 m east in 30 second and then returne to its starting point taking on additional 50 second .if west is chosen as the positive direction what will be the average speed of the object?
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An object moves 20 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction, what is the average speed of the object?
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3 Answers

John Privett, B.Sc. from Durham University (1979)
Answered 8 months ago · Author has 3.7K answers and 2.4M answer views
West being “the positive direction” is irrelevant. Speed is a scalar, not a vector quantity - it has magnitude but, unlike velocity, speed has no direction.
The object moves 20 metres east, and then back to the starting point. The question says nothing about the object’s path back to the starting point. I will assume it moves directly back to the starting point, so it moves a further 20 metres, making a total of 40 metres travelled.
If it takes some other path back to the starting point that would have to be explicitly stated to enable the question to be answered.
The time taken for the object to move is (30 + 50) = 80 seconds. Hence the average speed is 40/80 m/s. That’s 0.5 m/s.
If you’d asked for the average velocity then, taking the direction into account, since the object is back at its starting point it has travelled no distance. The average velocity is zero.