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Category: Vector

v-2i-2j-5k-r-i-9j-8k-Find-I-can-do-r-v-r-2-and-i-get-61i-21j-16k-146-but-i-dont-get-w-r-v-why-

Question Number 16401 by sushmitak last updated on 21/Jun/17 $$\boldsymbol{{v}}=\mathrm{2}\boldsymbol{{i}}+\mathrm{2}\boldsymbol{{j}}+\mathrm{5}\boldsymbol{{k}} \\ $$$$\boldsymbol{{r}}=\boldsymbol{{i}}+\mathrm{9}\boldsymbol{{j}}−\mathrm{8}\boldsymbol{{k}} \\ $$$$\mathrm{Find}\:\boldsymbol{\omega} \\ $$$$\mathrm{I}\:\mathrm{can}\:\mathrm{do}\:\frac{\boldsymbol{{r}}×\boldsymbol{{v}}}{{r}^{\mathrm{2}} }=\boldsymbol{\omega} \\ $$$$\mathrm{and}\:\mathrm{i}\:\mathrm{get}\:\boldsymbol{\omega}=\:\frac{\mathrm{61}\boldsymbol{{i}}−\mathrm{21}\boldsymbol{{j}}−\mathrm{16}\boldsymbol{{k}}}{\mathrm{146}} \\ $$$$\mathrm{but}\:\mathrm{i}\:\mathrm{dont}\:\mathrm{get}\:\boldsymbol{{w}}×\boldsymbol{{r}}=\boldsymbol{{v}}. \\ $$$${why}? \\ $$…

A-car-drives-due-north-at-50-km-hr-Wind-blows-due-North-West-at-50-2-km-hr-In-what-direction-a-flag-hoisted-on-the-roof-of-the-car-points-

Question Number 16363 by Tinkutara last updated on 21/Jun/17 $$\mathrm{A}\:\mathrm{car}\:\mathrm{drives}\:\mathrm{due}\:\mathrm{north}\:\mathrm{at}\:\mathrm{50}\:\mathrm{km}/\mathrm{hr}. \\ $$$$\mathrm{Wind}\:\mathrm{blows}\:\mathrm{due}\:\mathrm{North}-\mathrm{West}\:\mathrm{at}\:\mathrm{50}\sqrt{\mathrm{2}} \\ $$$$\mathrm{km}/\mathrm{hr}.\:\mathrm{In}\:\mathrm{what}\:\mathrm{direction},\:\mathrm{a}\:\mathrm{flag} \\ $$$$\mathrm{hoisted}\:\mathrm{on}\:\mathrm{the}\:\mathrm{roof}\:\mathrm{of}\:\mathrm{the}\:\mathrm{car}\:\mathrm{points}? \\ $$ Commented by ajfour last updated on 22/Jun/17…

Two-particles-1-and-2-move-with-constant-velocities-v-1-and-v-2-At-the-initial-moment-their-position-vectors-are-equal-to-r-1-and-r-2-How-must-these-four-vectors-be-interr

Question Number 16294 by Tinkutara last updated on 20/Jun/17 $$\mathrm{Two}\:\mathrm{particles},\:\mathrm{1}\:\mathrm{and}\:\mathrm{2},\:\mathrm{move}\:\mathrm{with} \\ $$$$\mathrm{constant}\:\mathrm{velocities}\:\overset{\rightarrow} {{v}_{\mathrm{1}} }\:\mathrm{and}\:\overset{\rightarrow} {{v}_{\mathrm{2}} }.\:\mathrm{At}\:\mathrm{the} \\ $$$$\mathrm{initial}\:\mathrm{moment},\:\mathrm{their}\:\mathrm{position}\:\mathrm{vectors} \\ $$$$\mathrm{are}\:\mathrm{equal}\:\mathrm{to}\:\overset{\rightarrow} {{r}_{\mathrm{1}} }\:\mathrm{and}\:\overset{\rightarrow} {{r}_{\mathrm{2}} }.\:\mathrm{How}\:\mathrm{must}\:\mathrm{these} \\…

Question-147162

Question Number 147162 by nadovic last updated on 18/Jul/21 Answered by liberty last updated on 18/Jul/21 $$\left(\mathrm{1}\right)\overset{\rightarrow} {{p}}=\frac{\mathrm{2}}{\mathrm{5}}\overset{\rightarrow} {{a}}+\frac{\mathrm{1}}{\mathrm{5}}\overset{\rightarrow} {{b}}+\frac{\mathrm{2}}{\mathrm{5}}\overset{\rightarrow} {{c}} \\ $$$$\left(\mathrm{2}\right)\overset{\rightarrow} {{p}}.\overset{\rightarrow} {{b}}=\overset{\rightarrow}…

Let-A-B-and-C-be-the-midpoints-of-the-sides-BC-CA-and-AB-of-the-triangle-ABC-Prove-that-AA-1-2-AB-AC-

Question Number 16055 by Tinkutara last updated on 17/Jun/17 $$\mathrm{Let}\:{A}',\:{B}'\:\mathrm{and}\:{C}'\:\mathrm{be}\:\mathrm{the}\:\mathrm{midpoints}\:\mathrm{of} \\ $$$$\mathrm{the}\:\mathrm{sides}\:{BC},\:{CA}\:\mathrm{and}\:{AB}\:\mathrm{of}\:\mathrm{the} \\ $$$$\mathrm{triangle}\:{ABC}.\:\mathrm{Prove}\:\mathrm{that} \\ $$$$\overset{\rightarrow} {{AA}'}\:=\:\frac{\mathrm{1}}{\mathrm{2}}\left(\overset{\rightarrow} {{AB}}\:+\:\overset{\rightarrow} {{AC}}\right) \\ $$ Answered by mrW1 last…