The amount of feedstuffs and water that a cow needs is measured on a per-day basis, not per hour. Even then it is really dependent on the individual animal itself, especially when it comes to water requirements. As far as feed is concerned, the maintenance requirement for a cow is around 2.5% if its body weight in dry matter ration per day. As-fed ration is variable depending on many things including moisture of the feed, physiological requirements of the cow, and the time of the year.
Protein requirements change from cow to cow, what level of growth or production that they are at. Protein is available to cattle through feedstuffs and the microorganism that grow in the rumen. Protein levels are not the same for each cow, please see the below link for further information.
One cow contains such a minute amount of the world's water that it is considered insignificant.
Maintenance requirements are 2.5% of a cow's body weight in dry matter ration per day.
Around 75 to 90% of a cow is made up of water.
Probably not even a cow at all.
no.
I moo cow
To my knowledge, cows can't smell water unless there is something in the water that would give it a scent. In the scenario you describe, the cow could probably but not defintely find the water tank, depending on the location of the water tank and the shape of the water tank, etc. If the cow is thirsty, this combined with natural curiosity will drive the animal to find the water. You should make sure the cow is getting the water by checking the water level in the tank. If it's not getting water, it will bawl/ moo a lot and then become quite ill and theoretically die eventually.
the water will become dirty
Depending on her size and her level of water consumption, a cow can expell around 20 L of urine per day. Usually, the more water a cow will drink the bigger her urine output.
A cow typically needs 7% (non-lactating cows) to 10% (lactating) of her body weight in water per day.