Natural Resources – Solutions

Why is the atmosphere essential for life?

Solution:

The atmosphere is essential for life for the following reasons:

Life-sustaining gases like oxygen and carbon dioxide, along with other gases and water vapour, from the atmosphere.

(i) Air is a bad conductor of heat and maintains the temperature. If the temperature on the earth rises suddenly, it may threaten the existence of life.

(ii) It prevents heat from escaping into outer space during nights.

Oscillations – Solutions

1) Which of the following examples represent simple harmonic motion and which represent periodic nut not simple harmonic motion?

(a)  The rotation of earth about its axis.

(b) Motion of an oscillating mercury column in a U tube

(c) Motion of a ball bearing inside a smooth curved bowl, when released from a point slightly above the lower most point.

(d)  General vibrations of a polyatomic molecule about its equilibrium position.

Solution:

(a) it is periodic, but not SHM , because it does not execute to and fro motion about a fixed point.

(b) it is SHM. When the liquid levels in the limbs is made unequal by applying external force and the force is removed, then the liquid columns in the U tube execute SHM.