Q. No.Equation of continuity is based on:
1.
Conservation of mass
2.
Conservation of energy
3.
Conservation of angular momentum
4.
None of these
An inverted bell lying at the bottom of a lake 47.6 m deep has 50 cm3 of air trapped in it. The bell is brought to the surface of the lake. The volume of the trapped air will be: (atmospheric pressure = 70 cm of Hg and density of Hg = 13.6 g/cm3)
1. 350 cm3
2. 300 cm3
3. 250 cm3
4. 22 cm3
A siphon in use is demonstrated in the following figure. The density of the liquid flowing in the siphon is 1.5 gm/cc. The pressure difference between the point P and S will be:
| 1. | 105 N / m | 2. | 2 × 105 N / m |
| 3. | Zero | 4. | Infinity |
The height of a mercury barometer is \(75 ~\text{cm}\) at sea level and \(50 ~\text{cm}\) at the top of a hill. The ratio of the density of mercury to that of air is \(10^4.\) The height of the hill is:
| 1. | \(250 ~\text m\) | 2. | \(2.5 ~\text {km}\) |
| 3. | \(1.25 ~\text {km}\) | 4. | \(750 ~\text m\) |
The value of g at a place decreases by 2%. Then, the barometric height of mercury:
| 1. | increases by 2%. | 2. | decreases by 2%. |
| 3. | remains unchanged. | 4. | sometimes increases and sometimes decreases. |
A barometer kept in a stationary elevator reads \(76 ~\text{cm}.\) If the elevator starts accelerating up, the reading will be:
1. zero
2. equal to \(76 ~\text{cm}\)
3. more than \(76 ~\text{cm}\)
4. less than \(76 ~\text{cm}\)
A body is just floating on the surface of a liquid. The density of the body is the same as that of the liquid. The body is slightly pushed down. What will happen to the body?
| 1. | It will slowly come back to its earlier position |
| 2. | It will remain submerged, where it was left |
| 3. | It will sink |
| 4. | It will come out violently |
If two pieces of metal when immersed in a liquid have equal upthrust on them, then:
| 1. | Both pieces must have equal weights |
| 2. | Both pieces must have equal densities |
| 3. | Both pieces must have equal volumes |
| 4. | Both are floating in the same depth |
The following figure shows the flow of liquid through a horizontal pipe. Three tubes \(A,\) \(B\) and \(C\) are connected to the pipe. The radii of the tubes \(A,\) \(B\) and \(C\) at the junction are respectively \(2~\text{cm},1~\text{cm}\) and \(2~\text{cm}.\) It can be said that:
| 1. | the height of the liquid in the tube \(A\) is maximum. |
| 2. | the height of the liquid in the tubes \(A\) and \(B\) is the same. |
| 3. | the height of the liquid in all three tubes is the same. |
| 4. | the height of the liquid in the tubes \(A\) and \(C\) is the same. |
There is a hole in the bottom of a tank having water. If the total pressure at the bottom is \(3\) atm \((1~\text{atm}=10^5~\text{N}/\text{m}^2),\) then the velocity of water flowing from the hole is:
1. \(\sqrt{400}~~\text{m/s}\)
2. \(\sqrt{600}~~\text{m/s}\)
3. \(\sqrt{60}~~\text{m/s}\)
4. none of these
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