Math Problem Statement

Combine the following two velocity vectors to find the resultant vector. Vector A = 200 $ % at 60° and Vector B = 100 $ % at 140° .

Solution

To combine the two vectors, we need to break each vector into its horizontal (x) and vertical (y) components and then sum the components.

Step 1: Decompose each vector into components.

For Vector A (200 m/s at 60°):

  • The horizontal component (Ax) is given by Ax=Acos(θA)A_x = A \cdot \cos(\theta_A).
  • The vertical component (Ay) is given by Ay=Asin(θA)A_y = A \cdot \sin(\theta_A).

Ax=200cos(60)=2000.5=100m/sA_x = 200 \cdot \cos(60^\circ) = 200 \cdot 0.5 = 100 \, \text{m/s} Ay=200sin(60)=2000.866=173.2m/sA_y = 200 \cdot \sin(60^\circ) = 200 \cdot 0.866 = 173.2 \, \text{m/s}

For Vector B (100 m/s at 140°):

  • The horizontal component (Bx) is given by Bx=Bcos(θB)B_x = B \cdot \cos(\theta_B).
  • The vertical component (By) is given by By=Bsin(θB)B_y = B \cdot \sin(\theta_B).

Bx=100cos(140)=100(0.766)=76.6m/sB_x = 100 \cdot \cos(140^\circ) = 100 \cdot (-0.766) = -76.6 \, \text{m/s} By=100sin(140)=1000.643=64.3m/sB_y = 100 \cdot \sin(140^\circ) = 100 \cdot 0.643 = 64.3 \, \text{m/s}

Step 2: Sum the components.

  • Resultant horizontal component (Rx): Rx=Ax+BxR_x = A_x + B_x
  • Resultant vertical component (Ry): Ry=Ay+ByR_y = A_y + B_y

Rx=100+(76.6)=23.4m/sR_x = 100 + (-76.6) = 23.4 \, \text{m/s} Ry=173.2+64.3=237.5m/sR_y = 173.2 + 64.3 = 237.5 \, \text{m/s}

Step 3: Find the magnitude of the resultant vector.

The magnitude RR is given by the Pythagorean theorem: R=Rx2+Ry2R = \sqrt{R_x^2 + R_y^2} R=(23.4)2+(237.5)2=547.56+56412.25=56959.81238.7m/sR = \sqrt{(23.4)^2 + (237.5)^2} = \sqrt{547.56 + 56412.25} = \sqrt{56959.81} \approx 238.7 \, \text{m/s}

Step 4: Find the direction of the resultant vector.

The direction (angle θR\theta_R) of the resultant vector is given by: θR=tan1(RyRx)\theta_R = \tan^{-1} \left( \frac{R_y}{R_x} \right) θR=tan1(237.523.4)tan1(10.15)84.3\theta_R = \tan^{-1} \left( \frac{237.5}{23.4} \right) \approx \tan^{-1}(10.15) \approx 84.3^\circ

Final Result:

The magnitude of the resultant vector is approximately 238.7 m/s, and its direction is 84.3°.

Would you like more details or have any questions?

Here are some related questions:

  1. How do you convert between polar and Cartesian coordinates for vectors?
  2. What is the difference between vector addition and scalar addition?
  3. How do you calculate the angle between two vectors?
  4. How would the problem change if Vector B were directed in the negative direction?
  5. How does the law of cosines apply to finding the magnitude of the resultant?

Tip: Always make sure the angles you use in trigonometric functions are consistent with your calculator's mode (degrees or radians).

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Math Problem Analysis

Mathematical Concepts

Vector Addition
Trigonometry
Pythagorean Theorem
Inverse Tangent

Formulas

Ax = A * cos(θA)
Ay = A * sin(θA)
Bx = B * cos(θB)
By = B * sin(θB)
R = sqrt(Rx^2 + Ry^2)
θR = tan^(-1)(Ry / Rx)

Theorems

Pythagorean Theorem
Trigonometric Functions
Inverse Tangent Function

Suitable Grade Level

Grades 10-12