Analogy.
Industrial cites: _______:: Windy places: dust particles.

With respect to Green House effect. Statement A: Clouds, dusts and humid nights are warmer than clear dust free day nights. Statement B: Clouds and dust particles produce green house effect.

Consider two particles A and B having equal charges and placed at some distance. The particle A is slightly displaced towards B. Does the force on B increase as soon as the particle A is displaced? Does the force on the particle A increase as soon as it is displaced?

Assertion : Mucous membrane immobilises the micro-organisms in the body. Reason : Microoganisms and dust particles entering the respiratory tract are trapped in the mucus.

Assume that a tunnel ils dug along a chord of the earth, at a perpendicular distance R/2 from the earth's centre where R is the radius of the earth. The wall of the tunnel is frictionless. a. Find the gravitational force exerted by the earth on a particle of mass m placed in the tunnel at a distance x from the centre of the tunnel. b. Find the component of this fore along the tunnel and perpendicular to the tunnel. c. Find the normal force exerted by the wall on the particle. d. Find the resultant force on the particle. e.Show that the motion of the particle in the tunnel is simple harmonic and find the time period.

Find whether the following sentences are true or false.If false Correct the statement: The amount of water vapour in the air is more in windy places then other areas.

Two particles of masses 1.0 kg and 2.0 kg are placed at a separation of 50 cm. Assuming that the only forces acting on the particles are their mutual gravitation find the initial acceleration of the two particles.

A tunnel is dug along a diameter of the earth. Find the force on a particle of mass m placed in the tunnel at a distance x from the centre.

Arrange the following statements in correct sequence: 1. These vapours condense to form tiny droplets of water. 2. The water droplets come together to form large water droplets. 3. The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies. 4. The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains. 5. Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees. 6. Warm air carrying clouds rises up. 7. Higher up in the atmosphere, the air is cool. 8. These droplets floating in the air along with the dust particles form clouds.

Two particles A and B having equal charges are placed at distance d apart. A third charged particle placed on the perpendicular bisector at a distance x will experience the maximum Coulomb’s force when :