Advertisements
Advertisements
प्रश्न
The sap in trees, which consists mainly of water in summer, rises in a system of capillaries of radius r = 2.5 × 10–5 m. The surface tension of sap is T = 7.28 × 10–2 Nm–1 and the angle of contact is 0°. Does surface tension alone account for the supply of water to the top of all trees?
Advertisements
उत्तर
Radius of capillarity r = `2.5 xx 10^-5` m
S = T = `7.8 xx 10^-2 Nm^-1`
g = 9.8 m/s2
h = `(25 cos θ)/(rpg)`
= `(2 xx 7.28 xx 10^-2 cos 0^circ)/(2.5 xx 10^-5 xx 10^3 xx 9.8)`
= `(2 xx 7.28 xx 10^(-2 + 5))/(25 xx 10^3 xx 98)`
h = `(104 xx 10^3)/(175 xx 10^3)`
= `104/175`
= 0.594 m
= 0.6 m
Most of the trees are more than 0.6 m in height. So capillary action alone cannot account for the rise of water in all other trees.
APPEARS IN
संबंधित प्रश्न
A raindrop of diameter 4 mm is about to fall on the ground. Calculate the pressure inside the raindrop. [Surface tension of water T = 0.072 N/m, atmospheric pressure = 1.013 x 105 N/m2 ]
Explain why A drop of liquid under no external forces is always spherical in shape
In a conical pendulum, a string of length 120 cm is fixed at rigid support and carries a mass
of 150 g at its free end. If the mass is revolved in a horizontal circle of radius 0.2 m around a
vertical axis, calculate tension in the string (g = 9.8 m/s2)
A body weighs 4.0 kg-wt on the surface of the Earth. What will be its weight on the surface of a plant whose mass is `1/8` th of the mass of the Earth and radius half `(1/2)` of that of the Earth?
By a surface of a liquid we mean
A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be
The contact angle between a solid and a liquid is a property of
(a) the material of the solid
(b) the material of the liquid
(c) the shape of the solid
(d) the mass of the solid
A liquid is contained in a vertical tube of semicircular cross section. The contact angle is zero. The force of surface tension on the curved part and on the flat part are in ratio
A 5.0 cm long straight piece of thread is kept on the surface of water. Find the force with which the surface on one side of the thread pulls it. Surface tension of water = 0.076 N m−1.
Define surface tension.
Obtain an expression for the capillary rise or fall using the forces method.
Describe an experiment to prove that friction depends on the nature of a surface.
Mention the S.I unit and dimension of surface tension.
A molecule of water on the surface experiences a net ______.
The upward force of 105 dyne due to surface tension is balanced by the force due to the weight of the water column and 'h' is the height of water in the capillary. The inner circumference of the capillary is ______.
(surface tension of water = 7 × 10-2 N/m)
Soap solution is used for cleaning dirty clothes because ______.
If a drop of liquid breaks into smaller droplets, it results in lowering of temperature of the droplets. Let a drop of radius R, break into N small droplets each of radius r. Estimate the drop in temperature.
This model of the atmosphere works for relatively small distances. Identify the underlying assumption that limits the model.
When an air bubble of radius r rises from the bottom to the surface of a lake, its radius becomes `(5r)/4`. Taking the atmospheric pressure to be equal to the 10 m height of the water column, the depth of the lake would approximately be ______.
(ignore the surface tension and the effect of temperature)
The surface tension of boiling water is ______.
