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:
v = 2.18m/s
Explanation:
In order to calculate the speed of Betty and her dog you take into account the law of momentum conservation. The total momentum before Betty catches her dog must be equal to the total momentum after.
Then you have:
(1)
M: mass Betty = 40kg
m: mass of the dog = 15kg
v1o: initial speed of Betty = 3.0m/s
v2o: initial speed of the dog = 0 m/s
v: speed of both Betty and her dog = ?
You solve the equation (1) for v:

The speed fo both Betty and her dog is 2.18m/s
Answer: 6m
Explanation: 6 is more than 3 and their both being measured by m
There is a 33% chance of a large earthquake off the coast of Oregon.
The two main concerns of a large earthquake are Gas fires and Tsunami .
Explanation:
Everytime a large earthquake hits in any other part of the world, We find a small earthquake hitting off the coast of Oregon.
So scientists feel that as United States is prone to Earthquakes, the people have to be prepared for such eventualities.
The main concern for this large earthquake is, that it might lead to gas leakages at homes that can start a gas fire, which might spread. So people have to be careful and check on any gas leakages.
Such large earthquakes can also lead to tsunami waves. So people have to take precautions and evacuate, if they are near the coastline.