HSC Science (Computer Science) 12th Standard Board Exam - Maharashtra State Board Important Questions

Find the total energy and binding energy of an artificial satellite of mass 800 kg orbiting at a height of 1800 km above the surface of the earth.

[G = 6.67 x 10^-11 S.I. units, Radius of earth : R = 6400 km, Mass of earth : M = 6 x 10²⁴ kg]

Define the angle of contact.

Water rises to a height 3.2 cm in a glass capillary tube. Find the height to which the same water will rise in another glass capillary having half area of cross section.

In which of the following substances, surface tension increases with increase in temperature ?

1. Copper
2. Molten copper
3. Iron
4. Molten iron

'n' droplets of equal size of radius r coalesce to form a bigger drop of radius R. The energy liberated is equal to...................

(T =Surface tension of water)

`(a) 4piR^2T[n^(1/3)-1]`

`(b) 4pir^2T[n^(1/3)-1]`

`(c) 4piR^2T[n^(2/3)-1]`

`(d)4 pir^2T[n^(2/3)-1]`

The surface tension of water at 0ºc is 75·5 dyne/cm. Find surface tension of water at 25°C. [ α for water = 0·0021/°C ]

Explain the rise of liquid in the capillary on the basis of pressure difference.

The escape velocity of a body from the surface of the earth is 11.2 km/s. If a satellite were to orbit close to the surface, what would be its critical velocity?

Derive an expression for acceleration due to gravity at depth ‘d’ below the earth’s surface.

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.)

Draw a neat, labelled diagram for a liquid surface in contact with a solid, when the angle of contact is acute.

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? 

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).

Two soap bubbles have radii in the ratio 4:3. What is the ratio of work done to blow these bubbles?

Define surface tension and surface energy.

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).

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.

If two capillary tubes of different diameters are partially dipped in the same liquid vertically, then the rise of liquid ______.

Draw a neat labelled diagram of rise of liquid in capillary tube showing different components of tension (force).

State Kepler's laws of planetary motion.