What do engineers need to ensure there is sufficient of when designing a roller coaster?

Mechanical Energy (required for each hill, loop, helix, etc.)

Remember the law of conservation of energy. As you travel on a roller coaster, your kinetic energy and gravitational potential energy changes but have the same total. Depending on the track and the friction on it, you need to make sure that the gravitational potential energy does not "overpower" its kinetic energy and that it ensures a consistent, smooth ride.

first thing first of the answer is with technology. second thing second thing is that the big bang theory did not happened u see they say it did but what they dont realize is that like dinasures are still a round they might deny it but they and look at these 12 foot human skelteons they find lets see didnt the bible say something about giants. hope this peace.