Answer:
remove contamination; pollution ; test ground water and dirt .
Answer:
The importance of international bureau of weights and measures are;
1. to bring unification of measurement system.
2. to establish and preserve fundamental international prototypes.
3. to verify national standards, etc.
Answer:

Explanation:
m = Mass of roller coaster = 2000 kg
r = Radius of loop = 24 m
v = Velocity of roller coaster = 18 m/s
g = Acceleration due to gravity = 
Normal force at the point will be

The force exerted on the track is
.