diff --git a/engg_mech/assignment/images/t_one_1.jpg b/engg_mech/assignment/images/t_one_1.jpg new file mode 100644 index 0000000..9520c36 Binary files /dev/null and b/engg_mech/assignment/images/t_one_1.jpg differ diff --git a/engg_mech/assignment/images/t_one_2.jpg b/engg_mech/assignment/images/t_one_2.jpg new file mode 100644 index 0000000..d760d67 Binary files /dev/null and b/engg_mech/assignment/images/t_one_2.jpg differ diff --git a/engg_mech/assignment/t_one.tex b/engg_mech/assignment/t_one.tex new file mode 100644 index 0000000..254f7fa --- /dev/null +++ b/engg_mech/assignment/t_one.tex @@ -0,0 +1,227 @@ +\documentclass{article} +\usepackage{amsmath} +\usepackage{amssymb} +\usepackage{siunitx} +\usepackage{graphicx} +\usepackage{wrapfig} +\graphicspath{{./images/}} +\begin{document} +\title{Engineering Mechanics} +\author{Ahmad Saalim Lone, 2019BCSE017} +\date{14 May, 2020} +\maketitle +\section*{Question 1} + +Triangle law of vector addition states that when two vectors are represented by +two sides of a triangle in magnitude and direction taken in same order then +third side of that triangle represents in magnitude and direction the resultant +of the vectors. + +\begin{align*} + P &= 48 N \\ + Q &= 60 N \\ + R^2 &= P^2 - Q^2 - 2PQ\cos{\ang{150}} \\ + R^2 &= 48^2 + 60^2 - 2\times 48 \times 60 \times (-0.866) \\ + R^2 &= 10892 \\ + R &= 104.36 \\ + \cos\theta &= \frac{{P^2 + R^2 - Q^2}}{2PR} \\ + \theta &= \ang{16.70} \\ + \text{R makes an angle of }(\ang{85} - \ang{16.70}) &= \ang{68.3} +\end{align*} + +\section*{Question 2} + +\begin{align*} + \text{For the $A = 80N$ force} \\ + A_x &= 80 \times \cos{\ang{40}} \\ + &= 61.28N \\ + A_y &= 80 \times \sin{\ang{40}} \\ + &= 51.42N \\ +\end{align*} + +\begin{align*} + \text{For the $B = 120N$ force} \\ + B_x &= 120 \times \cos{\ang{70}} \\ + &= 41.04N \\ + B_y &= 120 \times \sin{\ang{70}} \\ + &= 112.76N \\ +\end{align*} + +\begin{align*} + \text{For the $C = 150N$ force} \\ + C_x &= 150 \times \cos{\ang{165}} \\ + &= -122.87N \\ + C_y &= 150 \times \sin{\ang{165}} \\ + &= 86.036N \\ +\end{align*} + +\section*{Question 3} + +\begin{figure*}[h] + \centering + \includegraphics[width=0.5\textwidth]{t_one_1} +\end{figure*} + +\begin{align*} + \cos{\alpha} &= \frac{600}{650} \\ + &= 0.923 \\ + \sin{\alpha} &= \frac{250}{650} \\ + &= 0.384 +\end{align*} +\begin{align*} + T_1 + T_2 \sin \alpha + 360 \sin\ang{37} &= 480 N \\ + T_2 \cos \alpha &= 360 \cos \ang{37} +\end{align*} + +From here, +\begin{align*} + T_1 = \text{The tension in cable } BC &= 143.724 N \\ + T_2 = \text{The tension in cable } AC &= 311.5 N +\end{align*} + +\section*{Question 4} + +Draw Free body diagram of the lower pulley. +\begin{figure*}[h] + \centering + \includegraphics[width=0.5\textwidth]{t_one_2} +\end{figure*} + +\begin{align*} + \cos{\theta} &= \frac{0.75}{2.514} = 0.3 \\ + \sin{\theta} &= \frac{2.4}{2.514} = 0.954 \\ + 2P \cos{\theta} &= P \cos{\alpha} \\ + 2P \sin{\theta} + P\sin{\alpha} &= mg \\ + \text{From this we get} \\ + P &= 738.825 N \\ + \alpha &= 53.13N +\end{align*} + +\section*{Question 5} + +Moments about A +\begin{align*} + F_1 &= 250 \cos{\ang{30}} \times 2 = 433 Nm \\ + F_2 &= 300 \sin{\ang{60}} \times 5 = 1299.04 Nm \\ + F_3 &= 500 \times 1 Nm +\end{align*} + +Moments about B +\begin{align*} + F_1 &= 0 Nm \\ + F_2 &= 300 \cos{\ang{60}} \times 4 = 600 Nm \\ + F_3 &= 0 Nm +\end{align*} + +\section*{Question 6} + +\begin{center} +Tension in $AD$ is $481N$ \\ +Tension in $AB$ is $T_1N$ \\ +Tension in $AC$ is $T_2N$ \\ +Length of $AD$ is $6.5m$ \\ +Length of $AB$ is $7m$ \\ +Length of $AC$ is $7.4m$ \\ +\end{center} + +On vertical components + +\begin{align*} + P &= 481 \cos{\ang{30.51}} + T_1 \cos{\ang{35.87}} + T_2 \frac{5.6}{7.4} \\ + P &= 414.4 + 0.8 T_1 + 0.75 T_2 +\end{align*} + +On horizontal components + +\begin{align*} + T_1 \sin{\ang{36.87}} N &= T_2 \frac{4.837}{7.4} \sin{\ang{29.74}}N \\ + 0.6 \times T_1 &= 0.324 \times T_2 \\ + 481 \sin{\ang{30.51}} N &= T_2 \frac{4.837}{7.4} \cos{\ang{29.74}} N \\ + 242.2 &= 0.567 \times T_2 \\ + T_2 &= 430.6 \\ + T_1 &= 232.57 \\ + P &= 414.4 + 0.8 \times 242.57 + 0.75 \times 430.6 \\ + P &= 923.4 N +\end{align*} + +\section*{Question 7} +\begin{align*} + \sum{F_A} &= 0 \\ + T_{AB} + T_{AC} + T_{AD} + P &= 0 \\ + & \text{where P has only one direction that is $\hat{\imath}$} \\ + \overrightarrow{AB} &= -(960mm)\hat{\imath} - (240mm)\hat{\jmath} + (380mm)\hat{k} \\ + AB &= 1060 mm \\ + \overrightarrow{AC} &= -(960mm)\hat{\imath} - (240mm)\hat{\jmath} - (320mm)\hat{k}\\ + AC &= 1040 mm \\ + \overrightarrow{AD} &= - (960mm)\hat{\imath} + (720mm)\hat{\jmath} - (220mm)\hat{k}\\ + AD &= 1220 mm \\ + \overrightarrow{T_{AB}} &= T_{AB} \cdot \hat{AB} = T_{AB} \left(-\frac{48}{53} \hat{\imath} - \frac{12}{53} \hat{\jmath} + \frac{19}{53} \hat{k} \right) \\ + \overrightarrow{T_{AC}} &= T_{AC} \cdot \hat{AC} = T_{AC} \left(-\frac{12}{13} \hat{\imath} - \frac{3}{13} \hat{\jmath} - \frac{4}{13} \hat{k}\right) \\ + \overrightarrow{T_{AD}} &= T_{AD} \cdot \hat{AD} = \frac{305}{1220} \times \overrightarrow{AD} = (-240 \hat{\imath} + 180 \hat{\jmath} - 55 \hat{k}) N +\end{align*} + +We know +\begin{align*} + \sum F_A &= 0 \\ + -\frac{48}{53}T_{AB} - \frac{12}{13} T_{AC} - 240 + P &= 0 \;\text{(X-axis)} \\ + -\frac{12}{53}T_{AB} -\frac{3}{13} T_{AC} + 180 &= 0 \;\text{(Y-axis)} \\ + -\frac{19}{53}T_{AB} + \frac{4}{13} T_{AC} + 55 &= 0\;\text{(Z-axis)} \\ +\end{align*} + +By solving these equations, we get + +\begin{align*} + T_{AB} &= 446.71 N \\ + T_{AC} &= 341.71 N \\ + P &= 960 N +\end{align*} + +\section*{Question 8} + +Calculate the unit vector along each rope just like previous question. \\ +Coordinates of point $A, B, C, D$ +\begin{align*} + A &= 4 \hat{k} m \\ + B &= -1.5 \hat{\imath} m - 2 \hat{\jmath} m \\ + C &= 2 \hat{\imath} m + 3 \hat{\jmath} m \\ + D &= 2.5 \hat{\jmath} m +\end{align*} + +Position vectors of each rope is $reference = 0 \hat{\imath} + 0 \hat{\jmath} + 6 \hat{k}$ +\begin{align*} + \overrightarrow{r_{AB}} &= -1.5 \hat{\imath} - 6 \hat{k} \\ + |r_{AB}| &= 6.5 \\ + \overrightarrow{r_{AC}} &= 2 \hat{\imath} - 3 \hat{\jmath} - 6 \hat{k} \\ + |r_{AC}| &= 7 \\ + \overrightarrow{r_{AD}} &= 2.5 \hat{\jmath} - 6 \hat{k} \\ + |r_{AD}| &= 6.5 +\end{align*} + +Now direction of forces are along unit vectors: + +\begin{align*} + \hat{r_{AB}} &= -\frac{1.5}{6.5} \hat{\imath} - \frac{6}{6.5} \hat{k} \\ + \hat{r_{AC}} &= \frac{2}{7} \hat{\imath} - \frac{3}{7} \hat{\jmath} - \frac{6}{7} \hat{k} \\ + \hat{r_{AD}} &= \frac{2.5}{6.5} \hat{\jmath} - \frac{6}{7} \hat{k} +\end{align*} + +\[ + \sum F_A = 0 +\] +So, + +\begin{align*} + -0.231 F_{AB} + 0.286 F_{AC} &= 0 \\ + -0.308 F_{AB} - 0.429 F_{AC} + 0.385 F_{AD} &= 0 \\ + -0.923 F_{AB} - 0.857 F_{AC} - 0.923 F_{AD} &= -800 +\end{align*} + +On solving these three equations, we get + +\begin{align*} + F_{AB} &= 251.2N \\ + F_{AC} &= 202.9N \\ + F_{AD} &= 427.1 N +\end{align*} + +\end{document}