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Derive an expression for acceleration due to gravity at depth ‘d’ below the earth’s surface.
Concept: Variation in the Acceleration>Variation in Gravity with Altitude
Calculate the density of paraffin oil, if glass capillary of diameter 0.25 mm dipped in paraffin oil of surface tension 0.0245 N/m rises to a height of 4 cm. (Angle of contact of paraffin with glass = 28° and acceleration due to gravity = 9.8 m/s2.)
Concept: Capillarity and Capillary Action
Draw a neat, labelled diagram for a liquid surface in contact with a solid, when the angle of contact is acute.
Concept: Capillarity and Capillary Action
A hole is drilled half way to the centre of the Earth. A body is dropped into the hole. How much will it weigh at the bottom of the hole if the weight of the body on the Earth’s surface is 350 N?
Concept: Variation in the Acceleration>Variation in Gravity with Altitude
The total energy of free surface of a liquid drop is 2π times the surface tension of the liquid. What is the diameter of the drop? (Assume all terms in SI unit).
Concept: Surface Tension
Two soap bubbles have radii in the ratio 4:3. What is the ratio of work done to blow these bubbles?
Concept: Capillarity and Capillary Action
Define surface tension and surface energy.
Concept: Surface Tension
Prove that `g_h=g(1-"2h"/R)` where gh is the acceleration due to gravity at altitude h and h << R (R is the radius of the earth).
Concept: Variation in the Acceleration>Variation in Gravity with Altitude
If the Earth completely loses its gravity, then for any body _______.
(A) both mass and weight become zero.
(B) neither mass nor weight become zero.
(C) weight becomes zero but not the mass.
(D) mass becomes zero but not the weight.
Concept: Weightlessness
If two capillary tubes of different diameters are partially dipped in the same liquid vertically, then the rise of liquid ______.
Concept: Capillarity and Capillary Action
Draw a neat labelled diagram of rise of liquid in capillary tube showing different components of tension (force).
Concept: Capillarity and Capillary Action
State Kepler's laws of planetary motion.
Concept: Kepler’s Laws
The total free surface energy of a liquid drop is `pisqrt2` times the surface tension of the liquid. Calculate the diameter of the drop in S.l. unit.
Concept: Surface Tension
A soap bubble of radius 12 cm is blown. Surface tension of soap solution is 30 dyne/cm. Calculate the work done in blowing the soap bubble.
Concept: Capillarity and Capillary Action
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)
Concept: Surface Tension
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?
Concept: Surface Tension
Show that the surface tension of a liquid is numerically equal to the surface energy per unit
area.
Concept: Surface Tension
‘g’ is the acceleration due to gravity on the surface of the Earth and ‘R’ is the radius of the
Earth.
Show that acceleration due to gravity at height ‘h’ above the surface of the Earth is
`gh = g (R/(R+H))^2`
Concept: Variation in the Acceleration>Variation in Gravity with Altitude
A big drop of radius R is formed from 1000 droplets of water. The radius of a droplet will be _______
A) 10 R
B) R/10
C) R/100
D) R/1000
Concept: Surface Tension
State any two characteristics of the angle of contact
Concept: Surface Tension
