If a rock falls from a height of 50

Question

meters on​ Earth, the height H​ (in meters) after x seconds is approximately H(x)=50-4.9x^2

1. ​What is the height of the rock when x=1.6 ​seconds?

2. ​When is the height of the rock 5 meters?

3. When does the rock strike the​ ground?

I think the first one is 3.03 not sure if I'm right.

Answer 1

1. h=50-4.9*1.6^2

no, you are wrong.

Answer 2

thank you how do I set the the third question to get the answer.

Answer 3

h is zero when it hits the ground
h=50-4.9t^2

t= sqrt (50-h) / 4.9

Answer 4

1. 30.4