Can a sailing boat be propelled by air blown at the sails from a fan attached to the boat?Explain.

What waves produced by a motor boat sailing in water are:

Can a magnetic field line from a closed loop? Explain.

In a room containing air, heat, can go from one place to another by

What is an unpolarised ligth ?Explain with the help of a suitable ray diagram,how an unpolarised light can be polarised by reflection from a transparent medium.Write the expression for Brewster angle in terms of the refractive index of the denser medium.

A train, standing in a station-yard, blows a whistle of frequency 400 Hz in still air. The wind starts blowing in the direction from the yard to the station with a speed of 10 m s^-1 . What are the frequency, wavelength, and speed of sound for an observer standing on the station’s platform? Is the situation exactly identical to the case when the air is still and the observer runstowards the yard at a speed of 10 m s^-1 ? The speed of sound in still air can be taken as 340 m s ^-1 .

A man in a boat rowing away from a cliff 150m high takes 2 minutes to change the angle of elevation of the top of the cliff from 60^@ to 45^@ . The speed of the boat is

A man is rowing a boat up a stream w.r.t the shore. Is he doing a work? Explain.

Do you think an electromagnet can be used for separating plastic bags from the garbage heap? Explain.

Magnetic field lines can netiher emanate from a point nor end on a point. Yet the field lines outside a bar magnet do seem to start from the North pole and end on the South pole. Does the second fact contradict the first? Explain.