Answer:
19.8 m/s
Explanation:
Given:
Maximum vertical displacement of the object (H) = 20 m
Acceleration due to gravity (g) = 9.8 m/s²
At maximum height, the velocity of the object is 0 m/s for a moment. So, final velocity (v) at the maximum height is 0 m/s.
Now, let the initial velocity or velocity at launch be 'u' m/s.
Now, using the following equation of motion for vertical motion:
[tex]v^2=u^2-2gH[/tex]
Rewriting in terms of 'u', we get:
[tex]u^2=v^2+2gH\\\\u=\sqrt{v^2+2gH}[/tex]
Plug in the given values and solve for 'u'. This gives,
[tex]u=\sqrt{0+2\times 9.8\times 20}\\\\u=\sqrt{392}\\\\u=19.8\ m/s[/tex]
Therefore, the vertical velocity at the launch is 19.8 m/s.
