Given the speed and the distance, to find time you can use the formula speed is equal to distance over time. From there you can manipulate the equation for time to equal the distance divided by speed. Time is equal to 18.4 meters divided by 35m/s which equals 0.526 seconds.
Answer:

Explanation:
From the question we are told that
Radius of vertical r= 8m
Force exerted by passengers is 1/4 of weight
Generally the net force acting on top of the roller coaster is give to be

where


Generally the net force is given to be 




Mathematical we can now derive V




Therefore the speed of the roller coaster is given ton be 
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