An elevator is descending with uniform acceleration.To measure the acceleration, a person in the elevator drops a coin at momen the elevator strts. The coin is 6 ft asbove the floor of the elevator at the time it is dropped. The person observes that the coin strikes the floor in 1 second. Calculate these dta the acceleration of the elevator.

Explanation

For elevator and coin u=0 as the elevator descends down ward with acceleratiion a (say) the coin has to move more distance than 1.8 cm to strike the floor. Time takes t=1 sec
`S_e=ut+ 1/2 at^2
=0+ 1/2 g(1)^2=1/2 g`,
S_3 = ut+ 1/2 a`t^2`
= 0+ 1/2 a`(1)^2`= 1/2 a
`` Total distance covered by coin given by
`1.8+1/2 a= 1/2 g
rarr 1.8 + a/2= 9.8/2=4.9
rarr a/2= 4.9=1.8=3.1m
rarr a= 6.2 m/s^2
= 6.2xx3.28=20.34 ft/s^2`.