IIT JEE , AIEEE Forum - Physics , General

PATELTEJAS

an elevator is descending with uniform accelaration a ball is dropped from 6 feet at the time the elevator starts if the ball falls on floor after 1 sec calculate the accelaration of elevator

PATELTEJAS

use formula of motion

astronautameya

hey patel tejas,
all we need to do here is to take the net acc due to gravity to be (g-a).
now, it is a simple problem using 2nd eqn of motion.

S=ut+1/2 a t^2

rate if satisfied

hardcore_genius

Now as the ball take 1s 2 fall from 6 feet, hence applying second equation of motion, we get-

a = 12 ms-2

Now , its acceleration upwards is 12 - 10 = 2 ms-2

I have told upwards because if it were downwards then in no case it would have fallen in less than 1.2 s taking g =10 ms-2

So, elevator is moving down with upwards acc. of 2 ms-2

Rate me for my effort.......

hardcore_genius

Oh! I m extrmely sorry. I have mistakenly solved it for 6meters.
U can do it in the same way by converting feet into meter.
well 1 feet = 0.3048 m.
so, 6 feet = 1.8288 m
Now, apply just like above , u will get the answer.
(answer wiil now be changed & also its direction)

rte me if satisfied...

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