Explain the following observations: i) Water wets glass surface but does not wet the waxed glass surface.
ii) A steel needle placed carefully on the surface of water does not sink.
iii) A matchstick rubbed at one end with soap starts moving immediately in one direction when placed on the surface of water.
iv) The mass of a lump of goodies constant everywhre, but it'd weight is not.
v) Large mercury drops from oval balls on a glass slide

The characteristics of groundwater is said to be: are weak turbiditya constant temperaturechemical composition and almost overall absence of oxygen.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.