Question

Find the direction and magnitude of the vectors (a) A = (25m)x + (-12m)y(b) B = (2.0m)x + (15m)y and(c) A + B

Answer 1

`\begin{gathered} a)\theta=-25.6\degree;|A|=27.73m \\ b)\theta=82.4\degree;|B|=15.13m \\ c)\theta=6.3\degree^{};|A+B|=27.17m \end{gathered}`

Step-by-step explanation

To find the direction of a two-dimensional vector, we apply the formula:

`\theta=\tan ^(-1)((a_y)/(a_x))`

To find the magnitude of a two-dimensional vector, we apply the formula:

`|a|=\sqrt[]{(a^{}_y)^2+(a_x)^2}`

a) The direction of vector A is:

`\begin{gathered} \theta=\tan ^(-1)((-12m)/(25m)) \\ \theta=\tan ^(-1)(-0.48) \\ \theta=-25.6\degree \end{gathered}`

The magnitude of vector A is:

`\begin{gathered} |A|=\sqrt[]{(25m)^2+(-12m)^2} \\ |A|=\sqrt[]{625m^2+144m^2}=\sqrt[]{769m^2} \\ |A|=27.73m \end{gathered}`

b) The direction of vector B is:

`\begin{gathered} \theta=\tan ^(-1)((15m)/(2m)) \\ \theta=\tan ^(-1)(7.5) \\ \theta=82.4\degree \end{gathered}`

The magnitude of vector B is:

`\begin{gathered} |B|=\sqrt[]{(2.0m)^2+(15m)^2} \\ |B|=\sqrt[]{4m^2+225m^2}=\sqrt[]{229m^2} \\ |B|=15.13m \end{gathered}`

c) First, we have to find the sum of A and B:

`\begin{gathered} A+B=(25m)x+(-12m)y+(2.0m)x+(15m)y \\ A+B=(25m+2.0m)x+(-12m+15m)y \\ A+B=(27m)x+(3m)y \end{gathered}`

The direction of the vector (A + B) is:

`\begin{gathered} \theta=\tan ^(-1)((3m)/(27m)) \\ \theta=\tan ^(-1)(0.1111) \\ \theta=6.3\degree^{} \end{gathered}`

The magnitude of the vector (A + B) is:

`\begin{gathered} |A+B|=\sqrt[]{(27m)^2+(3m)^2} \\ |A+B|=\sqrt[]{729m^2+9m^2}=\sqrt[]{738m^2} \\ |A+B|=27.17m \end{gathered}`