10판/3. 벡터

3-22 할리데이 10판 솔루션 일반물리학

짱세디럭스 2019. 8. 8. 22:39

E:(6.00[m],+0.900[rad])F:(5.00[m],75.0)G:(4.00[m],+1.20[rad])H:(6.00[m],210) \begin{aligned} \vec E:& (6.00 \ut{m}, + 0.900\ut{rad})\\ \vec F:& (5.00 \ut{m}, -75.0^\circ)\\ \vec G:& (4.00 \ut{m},+ 1.20\ut{rad})\\ \vec H:& (6.00 \ut{m}, -210^\circ)\\ \end{aligned}

E=(6cos0.9)i^+(6sin0.9)j^F=(5cos75)i^+(5sin75)j^=(5223)i^+(522+3)j^G=(4cos1.2)i^+(4sin1.2)j^H=(6cos210)i^+(6sin210)j^=(33)i^+3j^ \begin{aligned} \vec E &= (6\cos0.9)\hat i + (6\sin0.9)\hat j\\ \vec F &= (5\cos-75^\circ)\hat i + (5\sin-75^\circ)\hat j\\ &=\(\frac{5}{2} \sqrt{2-\sqrt{3}}\)\hat i + \(-\frac{5}{2} \sqrt{2+\sqrt{3}}\)\hat j\\ \vec G &= (4\cos1.2)\hat i + (4\sin1.2)\hat j\\ \vec H &= (6\cos-210^\circ)\hat i + (6\sin-210^\circ)\hat j\\ &=\(-3\sqrt3\)\hat i + 3\hat j \end{aligned}
(a) r=?\vec r=? Ans=E+F+G+H=(6cos0.9+5223+4cos1.233)i^+(6sin0.9522+3+4sin1.2+3)j^1.28i^+6.60j^ \begin{aligned} \Ans =& \vec E + \vec F + \vec G + \vec H\\ =& \(6\cos0.9+\frac{5}{2} \sqrt{2-\sqrt{3}}+4\cos1.2-3\sqrt3\)\hat i\\ &+\(6\sin0.9-\frac{5}{2} \sqrt{2+\sqrt{3}}+4\sin1.2+3\)\hat j\\ \approx& 1.28\hat i + 6.60\hat j\\ \end{aligned}
(b) r=?r=? Ans=E+F+G+H=(6cos0.9+5223+4cos1.233)2+(6sin0.9522+3+4sin1.2+3)26.72[m] \begin{aligned} \Ans =& \vec E + \vec F + \vec G + \vec H\\ =& \sqrt{\(6\cos0.9+\frac{5}{2} \sqrt{2-\sqrt{3}}+4\cos1.2-3\sqrt3\)^2+\(6\sin0.9-\frac{5}{2} \sqrt{2+\sqrt{3}}+4\sin1.2+3\)^2}\\ \approx& 6.72\ut{m}\\ \end{aligned}
(c) θr=? in[]\theta_r=? \ \text{in} \ut{^\circ} θr=tan1(6sin0.9522+3+4sin1.2+36cos0.9+5223+4cos1.233)79.1 \begin{aligned} \theta_r=&\tan^{-1}\(\frac{6\sin0.9-\frac{5}{2} \sqrt{2+\sqrt{3}}+4\sin1.2+3}{6\cos0.9+\frac{5}{2} \sqrt{2-\sqrt{3}}+4\cos1.2-3\sqrt3}\)\\ \approx&79.1^\circ \end{aligned}
(d) θr=? in[rad]\theta_r=? \ \text{in} \ut{rad} θr=tan1(6sin0.9522+3+4sin1.2+36cos0.9+5223+4cos1.233)1.38[rad] \begin{aligned} \theta_r=&\tan^{-1}\(\frac{6\sin0.9-\frac{5}{2} \sqrt{2+\sqrt{3}}+4\sin1.2+3}{6\cos0.9+\frac{5}{2} \sqrt{2-\sqrt{3}}+4\cos1.2-3\sqrt3}\)\\ \approx&1.38\ut{rad} \end{aligned}