If [tex][tex]$v=5.00$[/tex][/tex] meters/second and is inclined equally to the negative direction of the [tex][tex]$x$[/tex]-axis[/tex] and [tex][tex]$y$[/tex]-axis[/tex], what is the value of [tex][tex]$v_y$[/tex][/tex]?

A. -3.53 meters/second
B. +3.53 meters/second
C. -4.33 meters/second
D. -2.50 meters/second



Answer :

To solve this problem, let's consider the situation where the velocity vector [tex]\( v \)[/tex] is equally inclined to the negative directions of both the [tex]\( x \)[/tex]-axis and the [tex]\( y \)[/tex]-axis.

The velocity vector [tex]\( \vec{v} \)[/tex] can be resolved into components along the [tex]\( x \)[/tex] and [tex]\( y \)[/tex] axes. Since it is equally inclined, the angle with each axis is [tex]\( 45^\circ \)[/tex].

Given:
[tex]\[ v = 5.00 \ \text{meters/second} \][/tex]

1. We know the vector is equally inclined to both axes, meaning it makes an angle of [tex]\( 45^\circ \)[/tex] with each axis. In such cases, the components of [tex]\( v \)[/tex] along the [tex]\( x \)[/tex] and [tex]\( y \)[/tex] directions ([tex]\( v_x \)[/tex] and [tex]\( v_y \)[/tex]) will have equal magnitudes but negative signs because they are in the negative directions.

2. The components of the velocity vector [tex]\( v \)[/tex] along the [tex]\( x \)[/tex] and [tex]\( y \)[/tex] axes can be found using trigonometric relations for a [tex]\( 45^\circ \)[/tex] angle:
[tex]\[ v_x = v \cos(45^\circ) \][/tex]
[tex]\[ v_y = v \cos(45^\circ) \][/tex]

Since [tex]\( \cos(45^\circ) = \frac{1}{\sqrt{2}} \)[/tex]:
[tex]\[ v_x = v \cdot \frac{1}{\sqrt{2}} \][/tex]
[tex]\[ v_y = v \cdot \frac{1}{\sqrt{2}} \][/tex]

3. Substituting the value of [tex]\( v = 5.00 \ \text{meters/second} \)[/tex]:

[tex]\[ v_y = 5.00 \cdot \frac{1}{\sqrt{2}} \][/tex]

[tex]\[ v_y = 5.00 \cdot \frac{\sqrt{2}}{2} \][/tex]

Simplifying the expression:

[tex]\[ v_y = 5.00 \cdot \frac{\sqrt{2}}{2} = 5.00 \cdot 0.7071 = 3.5355339059327378 \][/tex]

Since the vector is in the negative [tex]\( y \)[/tex]-direction:

[tex]\[ v_y = -3.5355339059327378 \ \text{meters/second} \][/tex]

Hence, the correct answer is:

A. -3.53 meters/second