Answer:
1) The greatest height attained by the ball equals 20.387 meters.
2) The time it takes for the ball to reach 15 meters approximately equals 1 second.
Explanation:
The greatest height will be attained when the ball stop's in the air and starts falling back to the earth.
thus using third equation of kinematics we obtain the height attained as
where
'v' is the final speed of the ball
'u' is the initial speed of the ball
'a' is the acceleration that the ball is under which in this case equals 9.81 
's' is the distance it covers
Thus for maximum height applying the values in the equation we get
Using the same equation we can find the speed of the ball when it reaches 15 meters of height as
the time it takes to reduce the velocity to this value can be found by first equation of kinematics as
Answer: Given:
Initial velocity= 36km/h=36x5/18=10m/s
Final velocity =54km/h=54x5/18=15m/s
Time =10sec
Acceleration = v-u/ t
=15-10/10=5/10=1/2=0.5 m/s2
Distance =s=?
From second equation of motion:
S=ut +1/2 at^2
=10*10+1/2*0.5*10*10
=100+25
=125m
So distance travelled 125m
Hope it helps you
Density = Mass/Volume
So, given mass = 20 g and volume = 40 cm^3
By substituting in above equation, Density = 20/40 = 0.5 g/cm^3
Hope it helps.
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<h3>What is a survey?</h3>
A survey is a useful tool based on population samples, which is used to make statistical analyses in a given investigation.
Differences in surveys are generally due to small sample sizes, which may lead to errors in the analysis of data.
In conclusion, the article is not found here but surveys are important because they are representative samples of a population.
Learn more about surveys here:
brainly.com/question/13624055
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