Respuesta :
Answer:
vDP = 21.7454 m/s
θ = 200.3693°
Explanation:
Given
vDE = 7.5 m/s
vPE = 20.2 m/s
Required: vDP
Assume that
vDE to be in direction of - j
vPE to be in direction of i
According to relative motion concept the velocity vDP is given by
vDP = vDE - vPE (I)
Substitute in (I) to get that
vDP = - 7.5 j - 20.2 i
The magnitude of vDP is given by
vDP = √((- 7.5)²+(- 20.2)²) m/s = 21.7454 m/s
θ = Arctan (- 7.5/- 20.2) = 20.3693°
θ is in 3rd quadrant so add 180°
θ = 20.3693° + 180° = 200.3693°
The magnitude of the resultant velocity is 21.55 m/s in the +x-axis and the direction is 69.61° counterclockwise from the +x-axis.
The magnitude of the resultant vectors of two perpendicular objects can be computed by using the formula:
[tex]\mathbf{|v_R| = \sqrt{(|v_1|)^2 + (|v_2|)^2}}[/tex]
From the given information;
- let the velocity of the rain with respect to the ground be [tex]\mathbf{v_{rg}}[/tex]; and
- the velocity of the car to the ground be = [tex]\mathbf{v_{cg}}[/tex]
∴
[tex]\mathbf{|v_R| = \sqrt{(|v_{rg}|)^2 + (|v_{cg}|)^2}}[/tex]
replacing the values, we have:
[tex]\mathbf{|v_R| = \sqrt{(7.5 \ m/s)^2 + (20.2 \ m/s)^2}}[/tex]
[tex]\mathbf{|v_R| = \sqrt{56.25 + 408.04}}[/tex]
[tex]\mathbf{|v_R| = \sqrt{464.29 \ m/s}}[/tex]
[tex]\mathbf{|v_R| =21.55 \ m/s}[/tex] in the +x-axis
The direction of the resultant velocity of the raindrop in counterclockwise direction i.e to the vertical direction is calculated by using the expression:
[tex]\mathbf{\theta = tan ^{-1} \Big |\dfrac{v_{cg}}{v_{rg}}\Big |}[/tex]
[tex]\mathbf{\theta = tan ^{-1} \Big |\dfrac{20.2}{7.5}\Big |}[/tex]
[tex]\mathbf{\theta = tan ^{-1} \Big |2.69\Big |}[/tex]
[tex]\mathbf{\theta = 69.61^0}[/tex]
Therefore, we can conclude that the magnitude of the resultant velocity is 21.55 m/s in the +x-axis and the direction is 69.61° counterclockwise from the +x-axis.
Learn more about the resultant vector here:
https://brainly.com/question/12784665?referrer=searchResults