There are missing data in the text of the problem (found them on internet):
- speed of the car at the top of the hill:

- radius of the hill:

Solution:
(a) The car is moving by circular motion. There are two forces acting on the car: the weight of the car

(downwards) and the normal force N exerted by the road (upwards). The resultant of these two forces is equal to the centripetal force,

, so we can write:

(1)
By rearranging the equation and substituting the numbers, we find N:

(b) The problem is exactly identical to step (a), but this time we have to use the mass of the driver instead of the mass of the car. Therefore, we find:

(c) To find the car speed at which the normal force is zero, we can just require N=0 in eq.(1). and the equation becomes:

from which we find
Boiling water is a common method used to sterilize water that may be contaminated. subjecting microbes to such high temperatures is an example of a(n) microbicidal technique.
A substance that eliminates microorganisms (such as bacteria) is known as microbicide and the techniques that involve destruction of microbes are known as microbicidal techniques.
The pathogen biofilm was effectively destroyed by the combined microbicidal effects of hot water (50, 60, or 70 °C) and 2% citric acid. It was discovered that the combination of hot water and citric acid caused sub-lethally harmed cells.
A fairly easy way to disinfect water is to boil it. The majority of dangerous organisms, notably viruses and bacteria that cause waterborne infections, are killed when water is heated to a high temperature of 100°C. The water must boil for at least 20 minutes in order to be most effective.
Hence, water that may be polluted is frequently sterilized by boiling. Using such high temperatures to kill germs is an example of a microbicidal method.
Learn more about Sterilization techniques here brainly.com/question/13062351
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Burning of gases is one the example of chemical change