A straight rod OABCD is strapped on to the end of a straight hose pipe H with ‘A’ at the nozzle of the pipe (figure). Strings are ties to the rod at B, C and D and are allowed to drop down vertically. The lengths of the strings at B, C and D to just touch the stream of water, streaming out of the hose pipe from its nozzle, are in the ratio

Question

G1 Physics · Accepted Answer

The water leaves the nozzle tangent to the rod. Relative to the straight tangent line, gravity makes the stream fall by Δy = ½gt². The distance measured along the rod from A is proportional to t because the component of water velocity along that direction is constant. Therefore the required vertical string length is proportional to the square of distance from A. Hence the lengths at B, C and D are in the ratio AB² : AC² : AD², option B.