Answer
1.4 seconds
Work Step by Step
The roof is 2.2m away and the coin initially starts at rest so v0 = 0. Relative to the customer (and therefore, the compartment also since they accelerate at the same rate), the coin is moving upwards at $2.4m/s^2$
To find how long it takes for the coin to travel 2.2m we use
$\Delta x = v0*t + (1/2)at^2 $ or
$2.2 = (1/2)(2.4)t^2 $ and find that t = 1.4s
