Math Problem Statement

Corresponding to the three sets of masses listed in Table 2.1 are three forces F1, F2, and F3. Determine their resultant analytically using the component method.

Force 1: 200g, 1.96 Newtons, East

Force 2: 300g, 2.94 Newtons, Northeast

Force 3: 500g, 4.90 Newtons, 60 degrees South of East

Solution

To determine the resultant force of the three forces using the component method, we will break each force into its horizontal (FxF_x) and vertical (FyF_y) components and then sum them up to get the total horizontal and vertical components. From these, we can determine the magnitude and direction of the resultant force.

Force 1: 1.96 N, East

Since this force is directed along the east axis, it has no vertical component.

  • F1x=1.96NF_{1x} = 1.96 \, \text{N}
  • F1y=0NF_{1y} = 0 \, \text{N}

Force 2: 2.94 N, Northeast

This force is directed at a 45-degree angle to the east (since Northeast implies a 45-degree angle between the horizontal and vertical axes).

  • Horizontal component: F2x=2.94×cos(45)=2.94×222.08NF_{2x} = 2.94 \times \cos(45^\circ) = 2.94 \times \frac{\sqrt{2}}{2} \approx 2.08 \, \text{N}
  • Vertical component: F2y=2.94×sin(45)=2.94×222.08NF_{2y} = 2.94 \times \sin(45^\circ) = 2.94 \times \frac{\sqrt{2}}{2} \approx 2.08 \, \text{N}

Force 3: 4.90 N, 60 degrees South of East

This force makes a 60-degree angle south of the east axis.

  • Horizontal component: F3x=4.90×cos(60)=4.90×0.5=2.45NF_{3x} = 4.90 \times \cos(60^\circ) = 4.90 \times 0.5 = 2.45 \, \text{N}
  • Vertical component: F3y=4.90×sin(60)=4.90×324.24NF_{3y} = 4.90 \times \sin(60^\circ) = 4.90 \times \frac{\sqrt{3}}{2} \approx 4.24 \, \text{N} (Since it's directed south, this component is negative.)

Thus, the components of Force 3 are:

  • F3x=2.45NF_{3x} = 2.45 \, \text{N}
  • F3y=4.24NF_{3y} = -4.24 \, \text{N}

Sum of Components:

Now, we sum up the horizontal and vertical components.

  • Ftotal x=F1x+F2x+F3x=1.96+2.08+2.45=6.49NF_{\text{total x}} = F_{1x} + F_{2x} + F_{3x} = 1.96 + 2.08 + 2.45 = 6.49 \, \text{N}
  • Ftotal y=F1y+F2y+F3y=0+2.084.24=2.16NF_{\text{total y}} = F_{1y} + F_{2y} + F_{3y} = 0 + 2.08 - 4.24 = -2.16 \, \text{N}

Resultant Force:

The magnitude of the resultant force is given by the Pythagorean theorem:

Fresultant=Ftotal x2+Ftotal y2=6.492+(2.16)242.13+4.6746.86.84NF_{\text{resultant}} = \sqrt{F_{\text{total x}}^2 + F_{\text{total y}}^2} = \sqrt{6.49^2 + (-2.16)^2} \approx \sqrt{42.13 + 4.67} \approx \sqrt{46.8} \approx 6.84 \, \text{N}

Direction of the Resultant Force:

The direction of the resultant force is given by the angle θ\theta with respect to the east axis (horizontal):

θ=tan1(Ftotal yFtotal x)=tan1(2.166.49)tan1(0.333)18.4\theta = \tan^{-1}\left(\frac{F_{\text{total y}}}{F_{\text{total x}}}\right) = \tan^{-1}\left(\frac{-2.16}{6.49}\right) \approx \tan^{-1}(-0.333) \approx -18.4^\circ

This angle is 18.4 degrees south of east.

Final Answer:

  • Magnitude of the resultant force: 6.84 N
  • Direction of the resultant force: 18.4 degrees south of east.

Would you like more details on any of the steps?

Here are 5 questions to think about next:

  1. What would happen if Force 2 were acting directly North instead of Northeast?
  2. How would the resultant force change if Force 1 were doubled in magnitude?
  3. Can you apply the component method for forces acting at non-right angles?
  4. What is the physical significance of the direction of the resultant force?
  5. How does changing the angle of a force affect its horizontal and vertical components?

Tip: Always ensure that your angles and directions are clearly referenced to a common axis (e.g., East or North) when solving vector problems.

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Math Problem Analysis

Mathematical Concepts

Vector Components
Trigonometry
Vector Addition

Formulas

F_x = F * cos(θ)
F_y = F * sin(θ)
Resultant Force = sqrt(F_x^2 + F_y^2)
θ = tan⁻¹(F_y / F_x)

Theorems

Pythagorean Theorem
Trigonometric Ratios

Suitable Grade Level

Grades 10-12