# Tank Problem – Which tank will be filled first?

The Question is –

• Air pressure is same on Liquid.
• flow rate of water pouring in tank 1 through tap is equal to the water going out through the opening.

Trick –  To Solve this problem simply remember that Liquid ( Water ) will be at same level irrespective of size and shape of container. Something like below.

1. First water in Tank 1 will get filled upto the connectivity of Tank 1 and Tank2. Then Water will start flowing in Tank 2.

2.  Now water in Tank 2 will get filled UpTo connectivity of Tank 2 and Tank 3. Now Water will start flowing in tank 3.

3. Now coming to tank 3,

• Here important thing to notice – Outlet of 3 and inlet of 4 are not at same level.
• Water will rise in tank 3 upto connectivity of tank 3 and tank 4.

• Now, outlet of Tank 3 is vertical and rises to top at tank 4. So due to this water will rise equally in height in tank 3 and pipe until the height ‘h’ is achieved. Where h is the height of water inlet of tank 4.After this height h is achieved, water will pour to tank 4.

• We discussed that – Water is always at same level. so tank 4 starts filling and reaches same point in tank 3

• Now both the tank 3 and 4 will fill simultaneously till they get fully filled.

Hence the answer is 3 and 4 both 🙂

• For Video Solution check our Video –

## 10 Replies to “Tank Problem – Which tank will be filled first?”

1. Kamal Shah

3rd Tank will be filled 1st, than 4th and later 2nd and than 1st.

• Logical Baniya

No – Think again. Look at our Solution. 3rd tank will be filled only till 80% later then Tank 4 will start filling. After 80% both will be filled simultaneously.

• Sushil Periwal

Correct

2. Queen

What if tank 2 has a block on tank 3. Would 2 not fill up at all, and one will fill first?

Or will two fill then one?

• Logical Baniya

Then Tank 2 will be filled first. Tank 1 will never get filled as tanks are open.
Water will start coming out from Tank 2 once Tank 2 and Tank1 reached the same level.
Hope this helps 🙂

3. Cleber

Vendo no desenho a passagem do 2 para o 3 está fechada OU não.

3 and 4 will fill at the same time becuse of a fisical law

3 and 4 will fill at the same time becuse of a fisical law

• moussa

i agree with you but i think 4 will fill Fraction of a second sooner, because the Pressure at the bottom of 3 is much than above of the 4 then maybe 4 fill sooner at least one molecule!! sooner i will try to experience too!!!

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