Explain why
A fluid flowing out of a small' hole in a vessel results in a backward thrust on the vessel

Bubbles of air coming out through water in glass vessel appears silvery to an observer standing by the sides Explain the reason.

A vessel is in the form of an inverted cone.Its height is 8 cm and the radius of its top,which is open,is 5 cm.It is filled with water up to the brim.When lead shots,each of which is a sphere of radius 0.5 cm are dropped into the vessel,one-fourth of the water floes out.Find the number of lead shots dropped in the vessel.

A hollow sphere filled with water is hung by a thread. If it has a small hole at the bottom through which water slowly goes out, how does the time period change ?

• Take a thick sheet of cardboard and make a small hole or narrow slit in its middle. • Allow sunlight to fall on the narrow slit. This gives a narrow beam of white light. • Now, take a glass prism and allow the light from the slit to fall on one of its faces as shown in Fig. • Turn the prism slowly until the light that comes out of it appears on a nearby screen. What do you observe? You will find a beautiful band of colours.

From a uniform disk of radius R, a circular hole of radius Rl 2 is cut out. The centre of the hole is at RI2 from the centre of the original disc. Locate the centre of gravity of the resulting flat body.

The rms speed of molecules of a gas in a vessel is 400 ms^-1 .If half of the gas leaks out at constant temperature. The rms speed of the remaining gas molecules will be