It is found that the time it takes for the projectile to hit the ground would be after 20 seconds.
The projectile would hit the ground when its height h(t), is equal to zero.
The given function that models its height is given by:
[tex]h(t) = -4.9t^2 + 98t.[/tex]
where h is the height in meters and t is the elapsed time in seconds.
Then,
h(t) = 0
[tex]-4.9t^2 + 98t = 0\\-4.9t(t - 20) = 0\\\\t - 20 = 0[/tex]
t = 20
Thus, The projectile hits the ground after 20 seconds.
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