Answer:
or a roller coaster loop, if it were perfectly circular, we would have a minimum speed of vmin=√gR at the top of the loop where g=9.8m/s2 and R is the radius of the 'circle'. However, most roller coaster loops are actually not circular but more elliptical.
Explanation:
 
        
             
        
        
        
Pretty sure its volcanic ash or magma, hope this helps
        
             
        
        
        
Answer:
Here the source is moving away from the observer so frequency will be smaller than the actual frequency and since the speed is increasing so the frequency is decreasing with time so correct answer is
D) lower than the original pitch and decreasing as he falls.
Explanation:
As we know by the Doppler's effect of sound we have
so we will have

so here when source moves away from the observer with a some speed then the frequency of the sound observed by the observer is smaller than the actual frequency
Here we know that the speed of the source is increasing with time as the source is falling under gravity
So we can say that the pitch of the sound will decrease with time
 
        
             
        
        
        
To be considered a source of water pollution, the source must include a chemical is false.
<u>Explanation:
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The water pollution may be caused either by chemicals or waste materials that doesn’t contain chemicals such as domestic wastes, organic compounds, heavy metals etc. The life on Earth mostly relies on water and air, and if these two gets polluted; the results will be dangerous.
Around 70% of the planet is covered with water and the present state of its purity is a matter of a serious thought. Looking over various pollutants, only chemical wastes are not responsible to pollute the water.
Instead, there is range of elements from plastic scraps to chemical wastes that comes from either the non-point sources or the point sources. There are organic waste materials, heavy metals, volcanic eruptions, Tsunamis, earthquakes, etc. are also responsible to contaminate water and affect the amphibians as well as humans.