a) The kinetic energy (KE) of an object is expressed as the product of half of the mass (m) of the object and the square of its velocity (v²):

It is given:
v = 8.5 m/s
m = 91 kg
So:

b) We can calculate height by using the formula for potential energy (PE):
PE = m*g*h
In this case, h is eight, and PE is the same as KE:
PE = KE = 3,287.4 J
m = 91 kg
g = 9.81 m/s² - gravitational acceleration
h = ? - height
Now, let's replace those:
3,287.4= 91 * 9.81 * h
⇒ h = 3,287.4/(91*9.81) = 3,287.4/892.7 = 3.7 m
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My answers
You need to check the temperature of food being stored in a temperature-controlled environment every four hours. The process of changing a space's temperature is called temperature control.
Cooking food alone may not be enough to avoid food poisoning, though, if the bacteria in food are allowed to grow to large numbers. When the temperature is between 5°C and 63°C, bacteria can grow. The risk zone is the range between 5°C and 63°C.
Temperature control is a process where the passage of heat energy into or out of a space or substance is adjusted to achieve the desired temperature. This process involves measuring or otherwise detecting changes in the temperature of the space (and all of the objects contained therein) or of the substance.
Learn more about temperature here
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Answer:
Option e) 320 s
Explanation:
Here, distance = 3.0 km = 3000 m
The velocity of boat when it is going upstream;
Upstream velocity = velocity of boat in still water - velocity of river flow
So, Upstream velocity 
So,Time to go upstream

The velocity of boat when it is going downstream;
Downstream velocity = velocity of boat in still water + velocity of river flow
So, Downstream velocity 
So,Time to go downstream

So, total time (t) = 
Option E is the correct answer.
All spontaneous processes release free energy