Q. No.The weight of an aeroplane flying in the air is balanced by
1. Vertical component of the thrust created by air currents striking the lower surface of the wings
2. Force due to reaction of gases ejected by the revolving propeller
3. Upthrust of the air which will be equal to the weight of the air having the same volume as the plane
4. Force due to the pressure difference between the upper and lower surfaces of the wings created by different air speeds on the surfaces
If there were a smaller gravitational effect, which of the following forces do you think would alter in some respect?
1. Viscous forces
2. Archimedes uplift
3. Electrostatic force
4. None of the above
A U tube with both ends open to the atmosphere,is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10mm above the water level on the other side. Meanwhile the water rises by 65 mm from its original level (see diagram). The density of the oil is
1.
2.
3.
4.
A rectangular film of liquid is extended from \((4~\text{cm} \times2 ~\text{cm})\) to \((5 ~\text{cm}\times 4 ~\text{cm})\). If the work done is \(3 \times 10^{-4}~\text{J},\) the value of the surface tension of the liquid is:
1. \(0.25\) N/m
2. \(0.125\) N/m
3. \(0.2\) N/m
4. \(8.0\) N/m
Three liquids of densities (with ), having the same value of surface tension T, rise to the same height in three identical capillaries. The angles of contact obey:
| 1. | \(\frac{\pi}{2}>\theta_1>\theta_2>\theta_3 \geq 0\) |
| 2. | \(0 \leq \theta_1<\theta_2<\theta_3<\frac{\pi}{2}\) |
| 3. | \(\frac{\pi}{2}<\theta_1<\theta_2<\theta_3<\pi\) |
| 4. | \(\pi>\theta_1>\theta_2>\theta_3>\frac{\pi}{2}\) |
Two non-mixing liquids of densities and \(n 𝜌 (n>1)\) are put in a container. The height of each liquid is \(h.\) A solid cylinder floats with its axis vertical and length \(pL (𝑝 < 1)\) in the denser liquid. The density of the cylinder is \(d.\) The density \(d\) is equal to:
1. \({[2+(n+1)p}] 𝜌\)
2. \([{2+(n-1)p}] 𝜌\)
3. \([{1+(n-1)p}] 𝜌\)
4. \([{1+(n+1)p}] 𝜌\)
The approximate depth of an ocean is 2700 m. The compressibility of water is 45.4 x 10-11 Pa-1 and density of water is 103kg/m3. What fractional compression of water will be obtained at the bottom of the ocean?
(1)0.8x10-2
(2)1.0x10-2
(3)1.2x10-2
(4)1.4x10-2
A wind with speed \(40~\text{m/s}\) blows parallel to the roof of a house. The area of the roof is \(250~\text{m}^2\). Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be: \(\left(\rho_{\text{air}}= 1.2~\text{kg/m}^3 \right)\)
1. \(4.8\times 10^{5}~\text{N}, ~\text{downwards}\)
2. \(4.8\times 10^{5}~\text{N}, ~\text{upwards}\)
3. \(2.4\times 10^{5}~\text{N}, ~\text{upwards}\)
4. \(2.4\times 10^{5}~\text{N}, ~\text{downwards}\)
The cylindrical tube of a spray pump has radius \(R,\) one end of which has \(n\) fine holes, each of radius \(r.\) If the speed of the liquid in the tube is \(v,\) then the speed of ejection of the liquid through the holes will be:
| 1. | \(\dfrac{vR^2}{n^2r^2}\) | 2. | \(\dfrac{vR^2}{nr^2}\) |
| 3. | \(\dfrac{vR^2}{n^3r^2}\) | 4. | \(\dfrac{v^2R}{nr}\) |
The heart of a man pumps 5 L of blood through the arteries per minute at a pressure of 150 mm of mercury. If the density of mercury is \(13.6\times 10^3\)kg/m3 and g =10 m/s2, then the power of heart in watt is:
1. 1.70
2. 2.35
3. 3.0
4. 1.50
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