Explain why
A spinning cricket ball in air does not follow a parabolic trajectory.

In which of the following examples of motion, can the body be considered approximately a point object : (a) a railway carriage moving without jerks between two stations. (b) a monkey sitting on top of a man cycling smoothly on a circular track. (c) a spinning cricket ball that turns sharply on hitting the ground. (d) a tumbling beaker that has slipped off the edge of a table.

Shown are several curves (fig. (a), (b), (c), (d), (e), (f)). Explain with reason, which ones amongst them can be possible trajectories traced by a projectile (neglect air friction).

Molecules in air in the atmosphere are attracted by gravitational force of the earth. Explain why all of them do not fall into the earth just like an apple falling from a tree.

Use the formula v= sqrt((gamma p)/(rho)) to explain why the speed of sound in air (a) is independent of pressure. (b) increases with temperature. (c ) increases with humidity

(i) A poor emitter has a large reflectivity . Explain why. (ii) A copper tumbler feels much colder than a wooden block on a cold day. Explain why. (iii) The earth would become so cold that life is not possible on it in the absence of the atmosphere. Explain why? (iv) Why clear nights are cooler than cloudy nights? Why does a piece of red glass when heated and taken out glow with green light? (vi) Why does the earth not become as hot as the sun although it has been receiving heat from the sun for ages? (vii) Animals curl into a ball when they are very cool. Why? (viii) Heat is generated continuously in an electric heater but its temperature becomes constant after some time. Explain why? (ix) A piece of paper wrapped tightly on a wooden rod is observed to get charred quickly when held over a flame as compared to a similar piece of paper when wrapped on a brass rod. Explain why? (x) Liquid in a metallic pot boils quickly whose base is made black and rough than in a pot whose base is highly polished . Why?

Explain - “To hit sixer the cricketer hit the ball by whirling the bat”.