A brick is thrown vertically from an aircraft flying two kilometres above earth.The brick will fall with a 

Newton's laws of motion does not hold good for objects

Which one of the following physical quantities is the same for molecules of all gases at a given temperature?

The focal length of the lens of a normal human eye is

X-rays are

A body is falling freely under the action of gravity alone in vaccuum.Which one of the following remains constant during a fall?