The wettability of a surface by a liquid depends primarily on:
1. | viscosity |
2. | surface tension |
3. | density |
4. | angle of contact between the surface and the liquid |
Water rises to height h in a capillary tube. If the length of the capillary tube above the surface of water is made less than h, then:
1. | water does not rise at all. |
2. | water rises up to the top of the capillary tube, then starts overflowing like a fountain. |
3. | water rises up to the top of the capillary tube and stays there without overflowing. |
4. | water rises up to a point a little below the top and stays there. |
A tank has an orifice near its bottom. The volume of the liquid flowing per second out of the orifice does not depend upon:
1. | the area of the orifice. | 2. | the height of the liquid level above the orifice. |
3. | the density of the liquid. | 4. | acceleration due to gravity. |
Which of the following diagrams does not represent a streamline flow?
1. | 2. | ||
3. | 4. |
(a) | gases decrease. | (b) | liquids increase. |
(c) | gases increase. | (d) | liquids decrease. |
Two small spherical metal balls, having equal masses, are made from materials of densities \(\rho_1\) and \(\rho_2\) such that and having radii of \(1\) mm and \(2\) mm, respectively. They are made to fall vertically (from rest) in a viscous medium whose coefficient of viscosity equals and whose density is \(0.1\). The ratio of their terminal velocities would be:
1. | 2. | ||
3. | 4. |
In a horizontal pipe of non-uniform cross-section, water flows with a velocity of 1 m s at a point where the diameter of the pipe is 20 cm. The velocity of water (m s) at a point where the diameter of the pipe is 5 cm is:
1. 8
2. 16
3. 24
4. 32
With an increase in temperature, the viscosity of liquid and gas, respectively will:
1. | increase and increase | 2. | increase and decrease |
3. | decrease and increase | 4. | decrease and decrease |
A capillary tube of radius \(r\) is immersed in water and water rises in it to a height \(h.\) The mass of the water in the capillary is \(5\) g. Another capillary tube of radius \(2r\) is immersed in water. The mass of water that will rise in this tube is:
1. | \(5.0\) g | 2. | \(10.0\) g |
3. | \(20.0\) g | 4. | \(2.5\) g |
The speed of flow past the lower surface of a wing of an aeroplane is \(50\) m/s. What speed of flow over the upper surface will give a dynamic lift of \(1000\) Pa? (density of air \(1.3\) kg/m3)
1. \(25.55\) m/s
2. \(63.55\) m/s
3. \(13.25\) m/s
4. \(6.35\) m/s