Answer:
V0 = 44.97m/s
Height above fence = 66.67m
Explanation:
The detailed calculation is done as shown in the attachment
Answer:
Energy converted = 
Explanation:
Recall that Power is the rate at which energy is transferred therefore defined by the mathematical formula: 
Since the information on the power of the runner is given, as well as the time the energy conversion takes place, we can then use this equation to find how much energy is been converted. Notice that we just need to change the given time *10 minutes) into the appropriate units (seconds)to get the answer in SI units of energy (Joules). The conversion of 10 minutes into seconds is done by multiplying : 10 minutes * 60 seconds/minute = 600 seconds.
We use this then to find the energy converted by the runner:

Given:
density of air at inlet, 
density of air at inlet, 
Solution:
Now,

(1)
where
A = Area of cross section
= velocity of air at inlet
= velocity of air at outlet
Now, using eqn (1), we get:

= 1.14
% increase in velocity =
=114%
which is 14% more
Therefore % increase in velocity is 14%
Answer:
1.5 m
Explanation:
Length. L = 12 m
Width, W = 16 m
Area, A = 12 x 16 = 192 m^2
Let the width of pavement be d.
The new length, L' = 12 + 2d
the new width, W' = 16 + 2d
New Area, A' = L' x W' = (12 + 2d)(16 + 2d) = 192 + 56 d + 4d^2
Difference in area = A' - A
285 = 192 + 56 d + 4d^2 - 192
93 = 56 d + 4d^2
4d^2 + 56 d - 93 = 0

\
d = 1.5 m
Thus, the width of the pavement is 1.5 m.