To develop this problem it is necessary to apply the equations concerning Bernoulli's law of conservation of flow.
From Bernoulli it is possible to express the change in pressure as
Where,
Velocity
Density
g = Gravitational acceleration
h = Height
From the given values the change of flow is given as
Therefore between the two states we have to
The flow rate will have changed to 54.77 % of its original value.
To solve this problem we will apply the concept related to the kinetic energy theorem. Said theorem states that the work done by the net force (sum of all forces) applied to a particle is equal to the change experienced by the kinetic energy of that particle. This is:
Here,
m = mass
v = Velocity
Our values are given as,
Replacing,
Therefore the mechanical energy lost due to friction acting on the runner is 907J