Answer:

Explanation:
v = Velocity of the breeze = 4 m/s
w = Width of the valley = 5000 m
h = Height of the valley = 1000 m
Volumetric flow rate is given by

= Mass flow rate of pollutant = 25 g/s = 
Concentration is given by

The steady state concentration of pollutants in the valley, is
.
Force equals mass time acceleration. Weight is a force and it can replace force in the equation. The acceleration would be gravity, which is an acceleration.
1.)
Fw (weight) = m (mass) · g (gravity, 9.8 m/s²)
Fw = m * 9.81 m/s²
560N = m · 9.81 m/s²
m ≈ 57.08 kg
2.)
d = 350 meters
t = 65 seconds
velocity = d/t
velocity = 350 meters / 65 seconds
velocity ≈ 5.38 meters/sec
3.)
Force = 35N
Distance = 2 meters
Work = Force · Distance
Work = 35N · 2 meters
Work = 70 J
They would be an expert in astronomy
astronomy:the branch of science that deals with celestial objects
She is

kilometers away from her starting point
I notice that even though we're working with frames of reference
here, you never said which frame the '5 km/hr' is measured in.
In fact ! You didn't even say which frame the '12 km/hr' of his
bike is measured in.
So there are several different ways this could go. I'll do it the way
I THINK you meant it, but that doesn't guarantee anything.
-- Simon is riding his bike at 12 km/hr relative to the sidewalk,
away from Keesha.
-- He throws a ball at Keesha, at 5 km/hr relative to his own face.
-- Keesha sees the ball approaching her at (12 - 5) = 7 km/hr
relative to the ground and to her.