Measurement tools make our lives safer and better? And they increase the quality and quantity of life. Arguably, the ability to measure calculating
physical properties accurately have tremendous survival value that gives humans adaptive, evolutionary advantages sharpened through many years of natural selection.
Answer:
D The chemicals on the right side of a chamical equation
We have the relation

where
denotes the velocity of a body A relative to another body B; here I use B for boat, E for Earth, and R for river.
We're given speeds


Let's assume the river flows South-to-North, so that

and let
be the angle made by the boat relative to East (i.e. -90° corresponds to due South, 0° to due East, and +90° to due North), so that

Then the velocity of the boat relative to the Earth is

The crossing is 153.0 m wide, so that for some time
we have

which is minimized when
so the crossing takes the minimum 30.0 s when the boat is pointing due East.
It follows that

The boat's position
at time
is

so that after 30.0 s, the boat's final position on the other side of the river is

and the boat would have traveled a total distance of

Answer:
a) the Tunguska meteoric impact
Explanation:
The Tunguska Event, sometimes known as the Tungus Meteorite is thought to have resulted from an asteroid or comet entering the earth's atmosphere and exploding. The event released as much energy as fifteen one-megaton atomic bombs. As well as blasting an enormous amount of dust into the atmosphere, felling 60 million trees over an area of more than 2000 square kilometres. Shaidurov suggests that this explosion would have caused "considerable stirring of the high layers of atmosphere and change its structure." Such meteoric disruption was the trigger for the subsequent rise in global temperatures
According to Vladimir Shaidurov of the Russian Academy of Sciences, the apparent rise in average global temperature recorded by scientists over the last hundred years or so could be due to atmospheric changes that are not connected to human emissions of carbon dioxide from the burning of natural gas and oil.
As we know,

so, let's solve for velocity (v)