Answer:
Hmax = 269.76 feet
Explanation:
This movement is vertical shot up.
We will accept value of g= 10m/s², but we must convert meters in the feets.
We know that 1 meter = 3.28 feets => 10meters = 32.8 feets
According to this g= 32.8 feet/s²
A flare is launched upwards from the height platform H₁ = 20 feet.
Initial velocity is 128 feet per second, when the flare reaches the highest point the final velocity is zero.
We will marked velocity with V and use this formula
V₀² - V² = 2 · g · H₂ and V= 0 => V₀² = 2 · g · H₂ => H₂ = V₀²/ 2 · g
H₂ = 128² / 2 · 32.8 = 16384 / 65.6 = 249.76 feet
The highest point in feet , that the flare reaches is:
Hmax = H₁ + H₂ = 20 + 249.6 = 269.6 feet.
God with you!!!