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
$${flag}\:{points}\:{in}\:{the}\:{direction}\:{of}\:{relative}\:{velocity}\:{of}\:{wind}\:{w}.{r}.{t}.\:{car}. \\ $$
Commented by prakash jain last updated on 21/Jun/17
$$\mathrm{Let}\:\mathrm{East}\:\mathrm{be}\:{i},\:\mathrm{North}\:\mathrm{will}\:\mathrm{be}\:{j}. \\ $$$$\mathrm{Car}\:\mathrm{Speed}\:=\:\mathrm{50}{j} \\ $$$$\mathrm{Wind}\:\mathrm{Speed}=\mathrm{50}{j}−\mathrm{50}{i} \\ $$$$\mathrm{Relative}\:\mathrm{velocity}\:\mathrm{of}\:\mathrm{wind}\:\mathrm{w}.\mathrm{r}.\mathrm{t}\:\mathrm{car} \\ $$$$\mathrm{speed}=\mathrm{50}{j}−\mathrm{50}{i}−\mathrm{50}{j}=−\mathrm{50}{i} \\ $$
Commented by Tinkutara last updated on 22/Jun/17
$$\mathrm{Sir},\:\mathrm{will}\:\mathrm{it}\:\mathrm{be}\:\mathrm{resultant}\:\mathrm{velocity}\:\mathrm{of}\:\mathrm{wind} \\ $$$$\mathrm{and}\:\mathrm{car}\:\mathrm{or}\:\mathrm{relative}\:\mathrm{velocity}\:\mathrm{of}\:\mathrm{wind} \\ $$$$\mathrm{w}.\mathrm{r}.\mathrm{t}\:\mathrm{car}\:\mathrm{that}\:\mathrm{is}\:\mathrm{needed}\:\mathrm{in}\:\mathrm{the}\:\mathrm{question}? \\ $$
Answered by ajfour last updated on 21/Jun/17
$$\:{Flag}\:{points}\:{due}\:{west}. \\ $$