Nội dung text Vector Varsity Daily-2 (Set-A) Solution.pdf
3 10. `ywU †f±‡ii jwäi m‡e©v”P gvb 40 N Ges GKwU †f±‡ii gvb 15 N n‡j, wb‡¤œi †Kvb gvbwU 2q †f±‡ii Rb ̈ cÖ‡hvR ̈ bq? [The maximum magnitude of the resultant of two vectors is 40 N and the magnitude of one of the vectors is 15 N. Which of the following values is not possible for the magnitude of the second vector?] 5 N 15 N 30 N All DËi: All e ̈vL ̈v: Rvwb, `ywU †f±i A I B n‡j Zv‡`i jwäi m‡e©v”P gvb, Rmax = |A| + |B| 40 = 15 + |B| Rmax = 40 N |A| = 15 N |B| = 25 N B Gi gvb 25 N n‡ZB n‡e Zv bv-n‡j Ab ̈wKQz cÖ‡hvR ̈ bq| 11. ABC GKwU wÎfzR| GLb, P I Q e‡ji jwä KZ? [ABC is a triangle. What is the resultant of forces P and Q?] 5N = Q P = 10 N A B C 60 175 N 60 N 75 N 80 N DËi: 75 N e ̈vL ̈v: Q = 5N P = 10 N A B C 60 R = P 2 + Q2 + 2PQ cos120 = 102 + 52 + 2 10 5 –1 2 = 100 + 25 – 50 = 75 N 12. A = 2i + 4j , B = 2j + 3k `ywU †f±i| GLb, C Ggb GKwU GKK †f±i wbY©q Ki hv Dc‡ii `ywU †f±‡ii mv‡_ j¤^fv‡e Aew ̄’Z? [Given vectors A = 2i + 4j and B = 2j + 3k find a unit vector C that is perpendicular to both A and B.] 6 7 i – 3 7 j + 3 7 k 5 7 i – 4 7 j + 2 7 k 6 7 i + 2 7 k – 3 7 j 4i + 3j + 7k DËi: 6 7 i + 2 7 k – 3 7 j e ̈vL ̈v: A B = i 2 0 j 4 2 k 0 3 = i (12) – j (6) + k (4) = 12i – 6j + 4k C = = A B |A | B = 12i – 6j + 4k 122 +(–6) 2 + 42 = 12i – 6j + 4k 196 = 12 14 i – 6 14 j + 4 14 k = 6 7 i – 3 7 j + 2 7 k 13. j i + i k + k j + j k = ? – i – j – k –j – k i + j 9i DËi: –j – k e ̈vL ̈v: j i = – k , i k = –j , k j = –i , j k = i = –k –j – i + i = –j – k 14. evwn ̈K evZvm _vK‡j Mvwoi KvP †fRvi kZ© hw` evZv‡mi w`K Mvwoi †e‡Mi w`‡K n‡j, †KvbwU mwVK? [If the speed of the wind is greater than the speed of the car, which part of the car's windshield will get wet?] VevZvm > VMvwo †cQ‡bi KuvP wfR‡e (Vair > Vcar Back windshield) VevZvm = VMvwo †Kvb KuvP wfR‡e bv (Vair = Vcar Neither windshield) VevZvm < VMvwo †cQ‡bi KuvP wfR‡e (Vair < Vcar Back windshield) †KvbwUB bq (None of the above) DËi: VevZvm > VMvwo †cQ‡bi KuvP wfR‡e e ̈vL ̈v: (i) evZvm I Mvwo/ ch©‡eÿK wecixZ w`‡K _vK‡j me©`vB mvg‡bi KuvP wfR‡e (ii) evZvm I Mvwo/ ch©‡eÿK GKB w`‡K _vK‡j Vc > Va n‡j mvg‡bi KuvP wfR‡e Vc < Va n‡j wcQ‡bi KuvP wfR‡e Vc = Va n‡j Dfq KuvP wfR‡e