Q. No.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
A square plate of 0.1 m side moves parallel to a second plate with a velocity of 0.1 m/s, both plates being immersed in water. If the viscous force is 0.002 N and the coefficient of viscosity is 0.01 poise, then the distance between the plates in m is:
| 1. | 0.1 | 2. | 0.05 |
| 3. | 0.005 | 4. | 0.0005 |
A spherical ball of radius \(r\) is falling in a viscous fluid of viscosity \(\eta\) with a velocity \(v.\) The retarding viscous force acting on the spherical ball is:
| 1. | inversely proportional to \(r\) but directly proportional to velocity \(v.\) |
| 2. | directly proportional to both radius \(r\) and velocity \(v.\) |
| 3. | inversely proportional to both radius \(r\) and velocity \(v.\) |
| 4. | directly proportional to \(r\) but inversely proportional to \(v.\) |
The pans of a physical balance are in equilibrium. If Air is blown under the right-hand pan then the right-hand pan will:
| 1. | move up | 2. | move down |
| 3. | move erratically | 4. | remain at the same level |
A sniper fires a rifle bullet into a gasoline tank making a hole 53.0 m below the surface of gasoline. The tank was sealed at 3.10 atm. The stored gasoline has a density of 660 . The velocity with which gasoline begins to shoot out of the hole will be:
| 1. | 27.8 ms-1 | 2. | 41.0 ms-1 |
| 3. | 9.6 ms-1 | 4. | 19.7 ms-1 |
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