Between the bumps and dips of two surfaces. SO the answer is 2 surfaces. Hope this helps! :)
Answer:
6.14 s
Explanation:
The time the rocket takes to reach the top is only determined from its vertical motion.
The initial vertical velocity of the rocket is:

where
u = 100 m/s is the initial speed
is the angle of launch
Now we can apply the suvat equation for an object in free-fall:

where
is the vertical velocity at time t
is the acceleration of gravity
The rocket reaches the top when

So by substituting into the equation, we find the time t at which this happens:

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