Explanation:
Drinking water requirement in town 2.0 m^3/s of water per second
nitrate in local well nitrate per 15
of water
nitrate in distant reservoir 
Let the flow rate of well
flow rate of reservoir 
Drinking water requirement is
or 
therefore, the total flow of drinking water
Answer:
4. It is the force of the road on the tires (an external force) that stops the car.
Explanation:
If there is no friction between the road and the tires, the car won't stop.
You can see this, for example, when there is ice on the road. You can still apply the brakes (internal force), but since there is no friction (external force) the car won't stop.
The force of the brakes on the wheels is not what makes the car stop, it is the friction of the road against still tires that makes it stop.
Answer:
The correct question is:
"Find the energy each gains"
The energy gained by a charged particle accelerated through a potential difference is given by

where
q is the charge of the particle
is the potential difference
For a proton,

And since 
The energy gained by the proton is

For an alpha particle,

Therefore, the energy gained is

Finally, for a singly ionized helium nucleus (a helium nucleus that has lost one electron)

So the energy gained is the same as the proton:

Longitudinal waves transfer energy parallel to the direction of the wave motion