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Rain is falling with a velocity `(-4hat(i)+8hat(j)-10hat(k))`. A person is moving with a velocity of `(6hat(i)+8hat(j))` on the ground. The speed with the rain drops hit the person is `:`A. `10m//s`B. `10sqrt(2)m//s`C. `sqrt(180)m//s`D. `sqrt(360)m//s` |
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Answer» Correct Answer - B `vec(V)_(rm)=vec(V)_(r)-vec(V)_(m)=(-10hat(i)-10hat(k))` Ans. `(-10hat(i)-10hat(k))` rain appears to come `45^(@)` with `hat (j)` `V_(m)=sqrt(10^(2)+10^(2))=10sqrt(2)m //sec.` `W_(CL)|_("accelerated motion") =DeltaKE-W_("friction")` where `W_(CL)` is work down by camel on load. `=[(1)/(2)mv^(2)-0]-[-mu_(kk) mg . 50]=1000[(125)/(2)]` similarly, `W_(CL)|_("acceleration")=DeltaKE-W_(f r iction)[0-(1)/(2)mv^(2)]-[-mu_(k)mg.50]=100[(75)/(2)]` `:. (W_(CL)|_("acceleration motion"))/(W_(CL)|_("retarded motion"))` `=(125)/(75)=(5)/(3)` `rArr 5:3` |
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