Answer:
a) "gravitation" is the force causing you to go down a waterslide
b) It is "fluid friction" as a solid object (our body) moves over a fluid (the water)
c) It would become "sliding friction" since two solid surfaces slide over each other
d) fluid friction being the weakest friction, switching to sliding friction means a higher decrease in speed and therefore removing the water from a slide will decrease our speed
I think it is "A'' 'It moves along straight lines in air and changes direction when it enters water.
Answer:3.49 m/s
Explanation:
Given
Speed of marble at Bottom 
Diameter of loop 
As Energy is conserved therefore Energy at top is equal to energy at bottom

,where
is the velocity at bottom







Answer:
a) Natural gas burns more efficiently and cleanly than other sources of carbon-based fossil fuels, thus contributing to a reduction in atmospheric carbon dioxide.
Explanation:
Although fossil fuels such as coal and oil have carbon content, natural gas also has it in smaller proportions, which is why it is a good idea to use it as a transitional fuel. Although natural gas does not have the same specific heat as gasoline, its production is simpler since it does not require the expensive refining processes such as petroleum derivatives, which is why its production is more efficient.
Another facility is the amount of natural gas that is obtained from oil wells, this can be extracted and stored efficiently to prevent its spread into the atmosphere.