ANSWER
5.08 seconds after being thrown
Step-by-step explanation
Given:
• The initial vertical velocity of the rock, u = 18 m/s
,
• The initial height of the rock, y₀ = 37 m
Find:
• The time it takes the rock to be at 2 m from ground level, t
The vertical displacement of an object is given by,

Where g is the acceleration of gravity, 9.8 m/s².
So, in this case, the height of the rock is given by the equation,

We have to find for what value of t, y = 2,

Subtract 2 from both sides,

To solve this equation, we can use the quadratic formula,

In this case, a = -4.9, b = 18, and c = 35,

The two possible solutions are,

Of these two results, t₂ is inconsistent with the problem. Remember that t represents time, so it cannot be negative.
Hence, we can conclude that the rock will be at 2 m from ground level 5.08 seconds after being thrown.