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A-balloon-moves-up-vertically-such-that-if-a-stone-is-projected-with-a-horizontal-velocity-u-relative-to-balloon-the-stone-always-hits-the-ground-at-a-fixed-point-at-a-distance-2u-2-g-horizontal

Question Number 18274 by Tinkutara last updated on 17/Jul/17 $$\mathrm{A}\:\mathrm{balloon}\:\mathrm{moves}\:\mathrm{up}\:\mathrm{vertically}\:\mathrm{such} \\ $$$$\mathrm{that}\:\mathrm{if}\:\mathrm{a}\:\mathrm{stone}\:\mathrm{is}\:\mathrm{projected}\:\mathrm{with}\:\mathrm{a} \\ $$$$\mathrm{horizontal}\:\mathrm{velocity}\:{u}\:\mathrm{relative}\:\mathrm{to}\:\mathrm{balloon}, \\ $$$$\mathrm{the}\:\mathrm{stone}\:\mathrm{always}\:\mathrm{hits}\:\mathrm{the}\:\mathrm{ground}\:\mathrm{at}\:\mathrm{a} \\ $$$$\mathrm{fixed}\:\mathrm{point}\:\mathrm{at}\:\mathrm{a}\:\mathrm{distance}\:\frac{\mathrm{2}{u}^{\mathrm{2}} }{{g}}\:\mathrm{horizontally} \\ $$$$\mathrm{away}\:\mathrm{from}\:\mathrm{it}.\:\mathrm{Find}\:\mathrm{the}\:\mathrm{height}\:\mathrm{of}\:\mathrm{the} \\ $$$$\mathrm{balloon}\:\mathrm{as}\:\mathrm{a}\:\mathrm{function}\:\mathrm{of}\:\mathrm{time}. \\ $$…

There-are-two-parallel-planes-each-inclined-to-the-horizontal-at-an-angle-A-particle-is-projected-from-a-point-mid-way-between-the-foot-of-the-two-planes-so-that-it-grazes-one-of-the-planes-and-st

Question Number 18271 by Tinkutara last updated on 01/Aug/17 $$\mathrm{There}\:\mathrm{are}\:\mathrm{two}\:\mathrm{parallel}\:\mathrm{planes},\:\mathrm{each} \\ $$$$\mathrm{inclined}\:\mathrm{to}\:\mathrm{the}\:\mathrm{horizontal}\:\mathrm{at}\:\mathrm{an}\:\mathrm{angle}\:\theta. \\ $$$$\mathrm{A}\:\mathrm{particle}\:\mathrm{is}\:\mathrm{projected}\:\mathrm{from}\:\mathrm{a}\:\mathrm{point}\:\mathrm{mid} \\ $$$$\mathrm{way}\:\mathrm{between}\:\mathrm{the}\:\mathrm{foot}\:\mathrm{of}\:\mathrm{the}\:\mathrm{two}\:\mathrm{planes} \\ $$$$\mathrm{so}\:\mathrm{that}\:\mathrm{it}\:\mathrm{grazes}\:\mathrm{one}\:\mathrm{of}\:\mathrm{the}\:\mathrm{planes}\:\mathrm{and} \\ $$$$\mathrm{strikes}\:\mathrm{the}\:\mathrm{other}\:\mathrm{at}\:\mathrm{right}\:\mathrm{angle}.\:\mathrm{Find} \\ $$$$\mathrm{the}\:\mathrm{angle}\:\mathrm{of}\:\mathrm{projection}\:\mathrm{of}\:\mathrm{the}\:\mathrm{projectile}. \\ $$ Commented…

The-flow-velocity-of-a-river-increases-linearly-with-the-distance-r-from-its-bank-and-has-its-maximum-value-v-0-in-the-middle-of-the-river-The-velocity-near-the-bank-is-zero-A-boat-which-can-move

Question Number 18269 by Tinkutara last updated on 17/Jul/17 $$\mathrm{The}\:\mathrm{flow}\:\mathrm{velocity}\:\mathrm{of}\:\mathrm{a}\:\mathrm{river}\:\mathrm{increases} \\ $$$$\mathrm{linearly}\:\mathrm{with}\:\mathrm{the}\:\mathrm{distance}\:\left({r}\right)\:\mathrm{from}\:\mathrm{its} \\ $$$$\mathrm{bank}\:\mathrm{and}\:\mathrm{has}\:\mathrm{its}\:\mathrm{maximum}\:\mathrm{value}\:{v}_{\mathrm{0}} \:\mathrm{in} \\ $$$$\mathrm{the}\:\mathrm{middle}\:\mathrm{of}\:\mathrm{the}\:\mathrm{river}.\:\mathrm{The}\:\mathrm{velocity} \\ $$$$\mathrm{near}\:\mathrm{the}\:\mathrm{bank}\:\mathrm{is}\:\mathrm{zero}.\:\mathrm{A}\:\mathrm{boat}\:\mathrm{which}\:\mathrm{can} \\ $$$$\mathrm{move}\:\mathrm{with}\:\mathrm{speed}\:{u}\:\mathrm{in}\:\mathrm{still}\:\mathrm{water}\:\mathrm{moves} \\ $$$$\mathrm{in}\:\mathrm{the}\:\mathrm{river}\:\mathrm{in}\:\mathrm{such}\:\mathrm{a}\:\mathrm{way}\:\mathrm{that}\:\mathrm{it}\:\mathrm{is} \\ $$$$\mathrm{always}\:\mathrm{perpendicular}\:\mathrm{to}\:\mathrm{the}\:\mathrm{flow}\:\mathrm{of}…

A-balloon-starts-rising-from-the-surface-of-earth-The-ascension-rate-is-constant-and-is-equal-to-v-0-Due-to-wind-the-balloon-gathers-horizontal-velocity-component-v-x-ay-where-a-is-a-positive-c

Question Number 18268 by Tinkutara last updated on 17/Jul/17 $$\mathrm{A}\:\mathrm{balloon}\:\mathrm{starts}\:\mathrm{rising}\:\mathrm{from}\:\mathrm{the}\:\mathrm{surface} \\ $$$$\mathrm{of}\:\mathrm{earth}.\:\mathrm{The}\:\mathrm{ascension}\:\mathrm{rate}\:\mathrm{is}\:\mathrm{constant} \\ $$$$\mathrm{and}\:\mathrm{is}\:\mathrm{equal}\:\mathrm{to}\:{v}_{\mathrm{0}} .\:\mathrm{Due}\:\mathrm{to}\:\mathrm{wind}\:\mathrm{the} \\ $$$$\mathrm{balloon}\:\mathrm{gathers}\:\mathrm{horizontal}\:\mathrm{velocity} \\ $$$$\mathrm{component}\:{v}_{{x}} \:=\:{ay},\:\mathrm{where}\:{a}\:\mathrm{is}\:\mathrm{a}\:\mathrm{positive} \\ $$$$\mathrm{constant}\:\mathrm{and}\:{y}\:\mathrm{is}\:\mathrm{the}\:\mathrm{height}\:\mathrm{of}\:\mathrm{ascent}. \\ $$$$\mathrm{Find} \\…

A-sky-diver-of-mass-m-drops-out-with-an-initial-velocity-v-0-0-Find-the-law-by-which-the-sky-diver-s-speed-varies-before-the-parachute-is-opened-if-the-drag-is-proportional-to-the-sky-diver-s-spee

Question Number 18264 by Tinkutara last updated on 17/Jul/17 $$\mathrm{A}\:\mathrm{sky}\:\mathrm{diver}\:\mathrm{of}\:\mathrm{mass}\:{m}\:\mathrm{drops}\:\mathrm{out}\:\mathrm{with} \\ $$$$\mathrm{an}\:\mathrm{initial}\:\mathrm{velocity}\:{v}_{\mathrm{0}} \:=\:\mathrm{0}.\:\mathrm{Find}\:\mathrm{the}\:\mathrm{law} \\ $$$$\mathrm{by}\:\mathrm{which}\:\mathrm{the}\:\mathrm{sky}\:\mathrm{diver}'\mathrm{s}\:\mathrm{speed}\:\mathrm{varies} \\ $$$$\mathrm{before}\:\mathrm{the}\:\mathrm{parachute}\:\mathrm{is}\:\mathrm{opened}\:\mathrm{if}\:\mathrm{the} \\ $$$$\mathrm{drag}\:\mathrm{is}\:\mathrm{proportional}\:\mathrm{to}\:\mathrm{the}\:\mathrm{sky}\:\mathrm{diver}'\mathrm{s} \\ $$$$\mathrm{speed}.\:\mathrm{Also}\:\mathrm{solve}\:\mathrm{the}\:\mathrm{problem}\:\mathrm{when}\:\mathrm{the} \\ $$$$\mathrm{sky}\:\mathrm{diver}'\mathrm{s}\:\mathrm{initial}\:\mathrm{velocity}\:\mathrm{has}\:\mathrm{horizontal} \\ $$$$\mathrm{component}\:{v}_{\mathrm{0}}…

A-particle-is-projected-at-an-angle-60-with-speed-10-3-m-s-from-the-point-A-as-shown-in-the-figure-At-the-same-time-the-wedge-is-made-to-move-with-speed-10-3-m-s-toward-right-as-shown-in-figure-

Question Number 18265 by Tinkutara last updated on 17/Jul/17 $$\mathrm{A}\:\mathrm{particle}\:\mathrm{is}\:\mathrm{projected}\:\mathrm{at}\:\mathrm{an}\:\mathrm{angle}\:\mathrm{60}° \\ $$$$\mathrm{with}\:\mathrm{speed}\:\mathrm{10}\sqrt{\mathrm{3}}\:\mathrm{m}/\mathrm{s}\:\mathrm{from}\:\mathrm{the}\:\mathrm{point}\:{A} \\ $$$$\mathrm{as}\:\mathrm{shown}\:\mathrm{in}\:\mathrm{the}\:\mathrm{figure}.\:\mathrm{At}\:\mathrm{the}\:\mathrm{same} \\ $$$$\mathrm{time}\:\mathrm{the}\:\mathrm{wedge}\:\mathrm{is}\:\mathrm{made}\:\mathrm{to}\:\mathrm{move}\:\mathrm{with} \\ $$$$\mathrm{speed}\:\mathrm{10}\sqrt{\mathrm{3}}\:\mathrm{m}/\mathrm{s}\:\mathrm{toward}\:\mathrm{right}\:\mathrm{as}\:\mathrm{shown} \\ $$$$\mathrm{in}\:\mathrm{figure}.\:\mathrm{Find}\:\mathrm{the}\:\mathrm{time}\:\mathrm{after}\:\mathrm{which} \\ $$$$\mathrm{particle}\:\mathrm{will}\:\mathrm{strike}\:\mathrm{the}\:\mathrm{wedge}. \\ $$ Commented…

What-is-the-maximum-angle-to-the-horizontal-at-which-a-stone-can-be-thrown-and-always-be-moving-away-from-the-thrower-

Question Number 18261 by Tinkutara last updated on 17/Jul/17 $$\mathrm{What}\:\mathrm{is}\:\mathrm{the}\:\mathrm{maximum}\:\mathrm{angle}\:\mathrm{to}\:\mathrm{the} \\ $$$$\mathrm{horizontal}\:\mathrm{at}\:\mathrm{which}\:\mathrm{a}\:\mathrm{stone}\:\mathrm{can}\:\mathrm{be} \\ $$$$\mathrm{thrown}\:\mathrm{and}\:\mathrm{always}\:\mathrm{be}\:\mathrm{moving}\:\mathrm{away} \\ $$$$\mathrm{from}\:\mathrm{the}\:\mathrm{thrower}? \\ $$ Answered by ajfour last updated on 26/Jul/17…

A-point-P-is-located-above-an-inclined-plane-It-is-possible-to-reach-the-plane-by-sliding-under-gravity-down-a-straight-frictionless-wire-joining-to-some-point-P-on-the-plane-How-should-P-be-cho

Question Number 18262 by Tinkutara last updated on 17/Jul/17 $$\mathrm{A}\:\mathrm{point}\:{P}\:\mathrm{is}\:\mathrm{located}\:\mathrm{above}\:\mathrm{an}\:\mathrm{inclined} \\ $$$$\mathrm{plane}.\:\mathrm{It}\:\mathrm{is}\:\mathrm{possible}\:\mathrm{to}\:\mathrm{reach}\:\mathrm{the}\:\mathrm{plane} \\ $$$$\mathrm{by}\:\mathrm{sliding}\:\mathrm{under}\:\mathrm{gravity}\:\mathrm{down}\:\mathrm{a}\:\mathrm{straight} \\ $$$$\mathrm{frictionless}\:\mathrm{wire}\:\mathrm{joining}\:\mathrm{to}\:\mathrm{some}\:\mathrm{point} \\ $$$${P}\:'\:\mathrm{on}\:\mathrm{the}\:\mathrm{plane}.\:\mathrm{How}\:\mathrm{should}\:{P}\:'\:\mathrm{be} \\ $$$$\mathrm{chosen}\:\mathrm{so}\:\mathrm{as}\:\mathrm{to}\:\mathrm{minimize}\:\mathrm{the}\:\mathrm{time} \\ $$$$\mathrm{taken}? \\ $$ Commented…