Magnitudes of two vectors $\overrightarrow{A}$ and $\overrightarrow{B}$ are $4$ units and $3$ units respectively. If these vectors are $(i)$ in the same direction $(\theta = 0^{\circ})$ and $(ii)$ in the opposite direction $(\theta = 180^{\circ})$,find the magnitude of the resultant vector in each case.
The magnitude of the resultant vector $\overrightarrow{R}$ of two vectors $\overrightarrow{A}$ and $\overrightarrow{B}$ is given by $R = \sqrt{A^2 + B^2 + 2AB \cos \theta}$.
$(i)$ When the vectors are in the same direction,$\theta = 0^{\circ}$. Thus,$R = \sqrt{4^2 + 3^2 + 2(4)(3) \cos 0^{\circ}} = \sqrt{16 + 9 + 24(1)} = \sqrt{49} = 7$ units.
$(ii)$ When the vectors are in the opposite direction,$\theta = 180^{\circ}$. Thus,$R = \sqrt{4^2 + 3^2 + 2(4)(3) \cos 180^{\circ}} = \sqrt{16 + 9 + 24(-1)} = \sqrt{25 - 24} = \sqrt{1} = 1$ unit.
$(i)$ When the vectors are in the same direction,$\theta = 0^{\circ}$. Thus,$R = \sqrt{4^2 + 3^2 + 2(4)(3) \cos 0^{\circ}} = \sqrt{16 + 9 + 24(1)} = \sqrt{49} = 7$ units.
$(ii)$ When the vectors are in the opposite direction,$\theta = 180^{\circ}$. Thus,$R = \sqrt{4^2 + 3^2 + 2(4)(3) \cos 180^{\circ}} = \sqrt{16 + 9 + 24(-1)} = \sqrt{25 - 24} = \sqrt{1} = 1$ unit.
Explore More
Similar Questions
The resultant of two forces acting at an angle of $120^{\circ}$ is $10 \,kg$-wt and is perpendicular to one of the forces. That force is
If three vectors have equal magnitude,i.e.,$A = B = C$,then the angle between $\vec{A}$ and $\vec{C}$ is $\alpha$. If $\vec{A} + \vec{B} + \vec{C} = 0$,then the angle between $\vec{A}$ and $\vec{C}$ is $\beta$. Find the ratio $\frac{\alpha}{\beta}$.
Let $\overrightarrow C = \overrightarrow A + \overrightarrow B$. Which of the following statements are correct?
$(A)$ It is possible to have $|\overrightarrow C| < |\overrightarrow A|$ and $|\overrightarrow C| < |\overrightarrow B|$.
$(B)$ $|\overrightarrow C|$ is always greater than $|\overrightarrow A|$.
$(C)$ $|\overrightarrow C|$ may be equal to $|\overrightarrow A| + |\overrightarrow B|$.
$(D)$ $|\overrightarrow C|$ is never equal to $|\overrightarrow A| + |\overrightarrow B|$.
$(A)$ It is possible to have $|\overrightarrow C| < |\overrightarrow A|$ and $|\overrightarrow C| < |\overrightarrow B|$.
$(B)$ $|\overrightarrow C|$ is always greater than $|\overrightarrow A|$.
$(C)$ $|\overrightarrow C|$ may be equal to $|\overrightarrow A| + |\overrightarrow B|$.
$(D)$ $|\overrightarrow C|$ is never equal to $|\overrightarrow A| + |\overrightarrow B|$.
Medium
View SolutionGiven that $A_1+A_2=5 A_3$ and $A_1-A_2=3 A_3$, where $A_3=2 \hat{i}+4 \hat{j}$, find the value of $\frac{|A_1|}{|A_2|}$.
Two forces of magnitude $3\;N$ and $4\;N$ respectively are acting on a body. Calculate the resultant force if the angle between them is $0^{\circ}$. (in $;N$)
Easy
View SolutionVedclass Products
For Students
Vedclass Test Series
Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.
Start Free TrialFor Teachers
Exam Paper Generator
Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.
Try FreeFor Institutes
Online Exam Module
Live online exams with unlimited students, 360° analytics & white-label branding.
See Demo