A lift is coming down from the 8^{th} floor a | vedclass

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Question

(A) The ground floor is the origin $(x = 0)$,and the upward direction is positive. Since the lift is between the ground floor and the $8^{th}$ floor,i

Vedclass · Accepted Answer

$x > 0, v  0$

Vedclass · Answer

(A) The ground floor is the origin $(x = 0)$,and the upward direction is positive. Since the lift is between the ground floor and the $8^{th}$ floor,its position $x$ is positive $(x > 0)$.As the lift is moving downwards,its velocity $v$ is in the negative direction,so $v Since the lift is about to stop at the $4^{th}$ floor,it must be decelerating (retarding). For a downward-moving object,deceleration means the acceleration $a$ must be in the opposite direction to the velocity,i.e.,in the upward (positive) direction. Therefore,$a > 0$.Thus,the correct signs are $x > 0, v  0$.

$A$ lift is coming down from the $8^{th}$ floor and is just about to reach the $4^{th}$ floor. Taking the ground floor as the origin and the upward direction as positive for all quantities,which one of the following is correct?

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