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Category: Mechanics

If-a-number-of-little-droplets-all-of-the-same-radius-r-coalesce-to-form-a-single-drop-of-radius-R-show-that-the-rise-in-temperature-is-given-by-3T-pJ-1-r-1-R-where-T-is-surface-tension

Question Number 51325 by peter frank last updated on 26/Dec/18 $${If}\:{a}\:{number}\:{of}\:{little}\: \\ $$$${droplets}\:{all}\:{of}\:{the}\:{same}\: \\ $$$${radius}\:{r}\:{coalesce}\:{to} \\ $$$${form}\:\:{a}\:{single} \\ $$$${drop}\:{of}\:{radius}\:{R}.{show} \\ $$$${that}\:{the}\:{rise}\:{in}\:{temperature} \\ $$$${is}\:{given}\:{by} \\ $$$$\frac{\mathrm{3}{T}}{{pJ}}\left(\frac{\mathrm{1}}{{r}}−\frac{\mathrm{1}}{{R}}\right)…

A-ball-is-bouncing-down-a-flight-of-stairs-The-coefficiate-of-restitution-is-e-The-height-of-each-step-d-and-the-ball-descends-one-step-at-each-bounce-After-each-bounce-it-rebounds-to-heigt-h-above

Question Number 51107 by peter frank last updated on 24/Dec/18 $${A}\:{ball}\:{is}\:{bouncing}\:{down} \\ $$$${a}\:{flight}\:{of}\:{stairs}.{The}\: \\ $$$${coefficiate}\:{of}\:{restitution} \\ $$$${is}\:{e}.{The}\:{height}\:{of}\:{each}\:{step} \\ $$$${d}\:{and}\:{the}\:{ball}\:{descends} \\ $$$${one}\:{step}\:{at}\:{each}\:{bounce}. \\ $$$${After}\:{each}\:{bounce}\:{it}\:{rebounds} \\ $$$${to}\:{heigt}\:\:{h}\:{above}\:{the}\:{next}…

Question-50973

Question Number 50973 by Necxx last updated on 22/Dec/18 Answered by mr W last updated on 22/Dec/18 $${see}\:{Q}\mathrm{50913}. \\ $$$${t}_{\mathrm{1}} =\mathrm{2}{e}\sqrt{\frac{\mathrm{2}{h}}{{g}}}=\mathrm{2}\left(\frac{\mathrm{3}}{\mathrm{4}}\right)\sqrt{\frac{\mathrm{2}×\mathrm{20}}{\mathrm{10}}}=\mathrm{3}\:{seconds} \\ $$ Commented by…

The-range-of-riffle-bullet-is-1000m-when-is-the-angle-of-projection-if-the-bullet-is-fired-with-the-same-angle-from-a-car-travelling-at-36km-h-towards-the-target-show-that-the-range-will-be-incre

Question Number 50915 by peter frank last updated on 22/Dec/18 $${The}\:{range}\:{of}\:{riffle}\:{bullet} \\ $$$${is}\:\mathrm{1000}{m}\:{when}\:\theta\:{is}\:{the}\:{angle} \\ $$$${of}\:{projection}.{if}\:{the}\:{bullet} \\ $$$${is}\:{fired}\:\:{with}\:{the}\:{same}\: \\ $$$${angle}\:\:{from}\:{a}\:{car}\:{travelling} \\ $$$${at}\:\mathrm{36}{km}/{h}\:{towards}\:{the}\:{target} \\ $$$${show}\:{that}\:{the}\:{range}\:{will} \\ $$$${be}\:{increased}\:{by}…

A-ball-is-dropped-from-height-h-it-strikes-the-ground-and-rises-the-coefficiate-of-restitution-being-e-what-is-the-total-distance-it-moves-and-the-time-before-it-comes-to-rest-

Question Number 50913 by peter frank last updated on 22/Dec/18 $${A}\:{ball}\:{is}\:{dropped}\:{from} \\ $$$${height}\:{h}.{it}\:{strikes}\:{the}\:{ground} \\ $$$${and}\:{rises},{the}\:{coefficiate} \\ $$$${of}\:{restitution}\:{being}\:\:{e} \\ $$$${what}\:{is}\:{the}\:{total}\:{distance} \\ $$$${it}\:{moves}\:\:{and}\:\:{the}\:{time}\: \\ $$$${before}\:{it}\:{comes}\:{to}\:{rest}? \\ $$$$…