Answer:
The hydro static force on the back of the dam is 
Explanation:
Given that,
Width b= 1000 m
Depth d= 200 m
We need to calculate the average pressure
Using formula of average pressure

Put the value into the formula


We need to calculate the hydro static force on the back of the dam
Using formula of force

Put the value into the formula


Hence, The hydro static force on the back of the dam is 
For the first part, we are looking for Vf when dy=11.0
Upward is positive, downward is negative.
So <span>Vf = square root [2(-9.8)(11.0) + (18.0)^2] </span>
<span>Vf = 10.4 m/s your answer is correct.
For the part b, t is equals to the time took to reach and dy is equals to 11.0
you did, </span>11= 18t m/s-(1/2) 9.8t^2 then <span>-11 + 18t- 9.8t^2. By quadratic formula, for the way down the answer is 2.9 s while on it's way up, the answer is 0.77 s</span><span>
</span>
(a) The height of the cliff will be 8.26 meters.
(b) The time would it take to reach the ground will be 0.717 sec.
<h3>What is velocity?</h3><h3 />
The change of displacement with respect to time is defined as the velocity. Velocity is a vector quantity. it is a time-based component.
(a) The height of the cliff will be 8.26 meters.
According to Newton's second equation of motion

Hence The height of the cliff will be 8.26 meters.
(b)The time would it take to reach the ground will be 0.717 sec.
We must have the final velocity to find the time so;

According to Newton's third equation of motion ;

Hence the time would it take to reach the ground will be 0.717 sec.
To learn more about the velocity refer to the link ;
brainly.com/question/862972
Answer:
60
Explanation:
Every 60 minutes is an hour