Question

You drop a rock down a well that is 5.4 m deep. How long does it take the rock to hit the bottom of the well?

Answer 1

1.05 s

Step-by-step explanation:

Answer 2

Equation of motion:


`y_(f)=y_(o)+v_(o)t+ (1)/(2) at^(2)`

Since initial velocity is zero, the second term goes away:


`y_(f)=y_(o)+0+ (1)/(2) at^(2)`


`y_(f)=y_(o)+(1)/(2) at^(2)`


`y_(f)-y_(o)= (1)/(2) at^(2)`


`y_(f)-y_(o)=5.4m`


`5.4m= (1)/(2) at^(2)`


`(2(5.4m) )/(a) = t^(2)`


`a = g = 9.81 (m)/( s^(2))`


`(2(5.4m) )/(9.81 (m)/( s^(2) ) ) = t^(2)`


`1.1 s^(2) = t^(2)`
`\sqrt{1.1 s^(2)} = \sqrt{t^(2)}`


`t = 1.05s`