State which of the following situations are possible and give an example for each of these. (a)An object with a constant acceleration but with zero velocity. (b) An object moving in a certain direction with an acceleration in the perpendicular direction.

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Chapter 7

NCERT

Class 9

Science

Solutions

9. State which of the following situations are possible and give an example for each of these.

Question:

State which of the following situations are possible and give an example for each of these.

(a) An object with a constant acceleration but with zero velocity.

(b) An object moving in a certain direction with an acceleration in the perpendicular direction.

Answer:

(a) The highest position of a ball thrown vertically upward is an example of this situation. The velocity of the ball at the highest position, is zero. But both the value and direction of it's acceleration g are constant. The value of this constant acceleration is, g = 9.8 ms–2 and it's direction is vertically downwards.

(b) This situation is not possible, because the direction of motion changes every moment, when the acceleration is perpendicular to the motion (velocity) and the particle cannot move in the same direction.

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