- #1
chennaivishnu
- 1
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Hi,
I have a garden which I water with the help of a garden hose, which drains water stored in a overhead tank (water tank at a certain height). Here is what I observe - when I partially close the tip of my gardern hose, the velocity of the water increases and hence the water reaches farther.
Now, here is my question on conservation of energy:
Suppose I fill the tank with 'm' kg of water and then I drain the entire tank once, with the hose normally held. And suppose V1 m/s was the average velocity of the water flowing out of the hose into the garden.
Then, I fill the tank again with 'm' kg of water and again drain it completely through the garden hose. But this time, I partially close the tip of the garden hose. So, this time, the velocity will be higher - say this time it is (V1 + v) m/s.
In the first case, the total kinetic energy of water at the tip of the hose will be 0.5mV1^2. In the second case, the total kinetic energy of water at the tip of the hose will be 0.5m(V1+v)^2, which is higer than the first one. But, in both the cases, the intial stored energy was the same and it was this stored energy that gave the kinetic energy at the tip of the hose. So, how come there is more KE in the second case? Where does the extra energy come from?!
I have a garden which I water with the help of a garden hose, which drains water stored in a overhead tank (water tank at a certain height). Here is what I observe - when I partially close the tip of my gardern hose, the velocity of the water increases and hence the water reaches farther.
Now, here is my question on conservation of energy:
Suppose I fill the tank with 'm' kg of water and then I drain the entire tank once, with the hose normally held. And suppose V1 m/s was the average velocity of the water flowing out of the hose into the garden.
Then, I fill the tank again with 'm' kg of water and again drain it completely through the garden hose. But this time, I partially close the tip of the garden hose. So, this time, the velocity will be higher - say this time it is (V1 + v) m/s.
In the first case, the total kinetic energy of water at the tip of the hose will be 0.5mV1^2. In the second case, the total kinetic energy of water at the tip of the hose will be 0.5m(V1+v)^2, which is higer than the first one. But, in both the cases, the intial stored energy was the same and it was this stored energy that gave the kinetic energy at the tip of the hose. So, how come there is more KE in the second case? Where does the extra energy come from?!