A ball is dropped from an elevator at an altitude of `200 m` (Fig.4. 39). How much time will the ball take to reach the ground if the elevatior is . a. Stationary? b. Ascending with velocity `10 m s^(-1)` c. Descending with velocity `10 m s^(-1)?

A ball is dropped from an elevator at an altitude of `200 m` (Fig.4. 3

1.	A ball is dropped from an elevator at an altitude of `200 m` (Fig.4. 39). How much time will the ball take to reach the ground if the elevatior is . a. Stationary? b. Ascending with velocity `10 m s^(-1)` c. Descending with velocity `10 m s^(-1)?
Answer» a. `s=ut+(1)/(2)at^(2) rArr -200=0 xx+(1)/(2) (-10)t^(2)` `rArr t=sqrt40 s` b. `-200=10t-(1)/(2) t^(2)` `rArr t^(2)-2t-40=0 rArr t=1+sqrt41 s` c. `-200=-10t-(1)/(2) 10t^(2) rArr t^(2)+2t-40=0` `rArr t=-t+ sqrt41 s`.

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A ball is dropped from an elevator at an altitude of `200 m` (Fig.4. 39). How much time will the ball take to reach the ground if the elevatior is . a. Stationary? b. Ascending with velocity `10 m s^(-1)` c. Descending with velocity `10 m s^(-1)?

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