maximum allowed value of the speed in roller coaster is given as

now from kinematics we can say

here initial speed will be

acceleration is due to gravity

now we can use this to find the height



so maximum allowed height will be 20.4 m
Answer: Water can either increase or decrease the friction between surfaces.
Yes a perch is a consumer.
Who created the theory of general relativity?:
The answer would be: Albert Einstein.
Albert Einstein developed the general relativity theory (gravitation).
The year he developed the general relativity theory or (GR) was back in 1907 and 1915. Then many other contributions after 1915.
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