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Category: Heat and Theromdynamics

A-vacuum-chamber-has-a-door-with-surface-dimensions-20cm-20cm-How-many-70kg-men-each-exerting-a-pull-equal-to-his-weight-will-it-take-to-pull-the-door-open-when-the-chamber-is-evacuated-to-a-pressure

Question Number 31474 by NECx last updated on 09/Mar/18 $${A}\:{vacuum}\:{chamber}\:{has}\:{a}\:{door} \\ $$$${with}\:{surface}\:{dimensions} \\ $$$$\mathrm{20}{cm}×\mathrm{20}{cm}.{How}\:{many}\:\mathrm{70}{kg}\:{men}, \\ $$$${each}\:{exerting}\:{a}\:{pull}\:{equal}\:{to}\:{his} \\ $$$${weight},{will}\:{it}\:{take}\:{to}\:{pull}\:{the} \\ $$$${door}\:{open}\:{when}\:{the}\:{chamber}\:{is} \\ $$$${evacuated}\:{to}\:{a}\:{pressure}\:{of}\:\mathrm{0}.\mathrm{1}\:{atm}? \\ $$ Commented…

A-student-seals-200g-of-ice-cold-water-in-a-glass-vacuum-thermos-flask-and-finds-that-it-warms-up-by-3-5-K-in-one-hour-SHC-of-water-2400-Jkg-1-K-1-a-Calculate-the-average-rate-of-heat-flow

Question Number 75648 by Rio Michael last updated on 14/Dec/19 $$\:{A}\:{student}\:{seals}\:\mathrm{200}{g}\:{of}\:{ice}−{cold}\:{water}\:{in}\:{a}\:{glass}\:{vacuum} \\ $$$$\left({thermos}\right)\:{flask}\:{and}\:{finds}\:{that}\:{it}\:{warms}\:{up}\:{by}\:\mathrm{3}.\mathrm{5}\:{K}\:{in}\:{one}\:{hour} \\ $$$${SHC}\:{of}\:{water}\:=\mathrm{2400}\:{Jkg}^{−\mathrm{1}} {K}^{−\mathrm{1}} \\ $$$$\left.{a}\right)\:{Calculate}\:{the}\:{average}\:{rate}\:{of}\:{heat}\:{flow}\:{in}\:{the}\:{flask}\:{in}\:{watts}. \\ $$$${To}\:{check}\:{this}\:{result}\:{over}\:{a}\:{longer}\:{period},{the}\:{student}\:{fills}\:{the}\:{flask}\:{with} \\ $$$${equal}\:{amounts}\:{of}\:{ice}\:{and}\:{water}\:{all}\:{at}\:\mathrm{0}°{C},\:{and}\:{leaves}\:{it}\:{for}\: \\ $$$$\mathrm{4}\:{hours}.\:{the}\:{specific}\:{latent}\:{heat}\left({enthalpy}\right)\:{of}\:{fusion}\:{of}\:{ice}\:{is}\:\mathrm{0}.\mathrm{33}{MJg}^{−\mathrm{1}} \\…

A-gap-must-be-left-between-steel-rails-to-allow-for-thermal-expansion-How-large-a-gap-is-needed-if-the-maximum-temperature-reached-is-50-above-the-temperature-at-which-the-rails-were-laid-The-

Question Number 141111 by jlewis last updated on 15/May/21 $$\mathrm{A}\:\mathrm{gap}\:\mathrm{must}\:\mathrm{be}\:\mathrm{left}\:\mathrm{between}\:\mathrm{steel}\: \\ $$$$\mathrm{rails}\:\mathrm{to}\:\mathrm{allow}\:\mathrm{for}\:\mathrm{thermal}\:\mathrm{expansion}. \\ $$$$\:\mathrm{How}\:\mathrm{large}\:\mathrm{a}\:\mathrm{gap}\:\mathrm{is}\:\mathrm{needed}\:\mathrm{if}\:\mathrm{the}\: \\ $$$$\mathrm{maximum}\:\mathrm{temperature}\:\mathrm{reached} \\ $$$$\:\mathrm{is}\:\mathrm{50}°\:\mathrm{above}\:\mathrm{the}\:\mathrm{temperature}\:\mathrm{at}\: \\ $$$$\mathrm{which}\:\mathrm{the}\:\mathrm{rails}\:\mathrm{were}\:\mathrm{laid}.\:\mathrm{The}\: \\ $$$$\mathrm{length}\:\mathrm{of}\:\mathrm{the}\:\mathrm{rail}\:\mathrm{is}\:\mathrm{10m}\:\mathrm{and} \\ $$$$\:\mathrm{the}\:\alpha_{\mathrm{steal}} =\mathrm{12}×\mathrm{10}^{−\mathrm{6}}…

Question-75203

Question Number 75203 by jagannath.02 last updated on 08/Dec/19 Answered by Rio Michael last updated on 08/Dec/19 $$\:{if}\:{we}\:{increase}\:{the}\:{temperature}\:{of}\: \\ $$$${a}\:{diatomic}\:{gas},\:{the}\:{molecules}\:{gain}\:{energy} \\ $$$${and}\:{move}\:{randomly}\:{applying}\:{more}\:{pressure}. \\ $$$${from}\:{the}\:{graph}\:{ab}\:{shows}\:{how}\:{temperature}\:{increases}. \\…