Why are we able to sip hot tea or milk faster from a saucer rather than a cup?

Why is a normal eye not able to see clearly the objects placed closer than 25 cm?

Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

It is easier to revolve a stone by attaching it to a shorter string rather than- to a longer one. Why?

Explain why Aquatic species are more comfortable in cold water rather than in warm water.

Why do we place handles at maximum possible distance from the hinges in a door?

Why are we not able to rotate a wheel by pulling or pushing along its radius?

A bigger rain drop falls faster than smaller one. Why ?

Why velocity of hot water is greater than velocity of cold water.

We wish to obtain an erect image of an object, using a concave mirror of focal length 15cm. What should be the range of distance of the object from the mirror? What is the nature of the image? Is the image larger or smaller than the object? Draw a ray diagram to show the image formation in this case.