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Grade 12th passMechanics

6 forces 20N ,30 N ,25N, 10N and 40N are acting along the sides of a regular hexagon ,taken in order.find the magnitude and direction of an resultant

Profile image of Sradhanjlai tripathy
5 Years agoGrade 12th pass
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ApprovedApproved Tutor Answer1 Year ago

To find the resultant of the forces acting along the sides of a regular hexagon, we need to break down the problem into manageable steps. A regular hexagon has six sides, and if we label the forces acting on each side, we can use vector addition to determine the resultant force. Let's go through this step by step.

Understanding the Forces

We have six forces acting along the sides of a regular hexagon, which we can denote as follows:

  • Force 1: 20 N
  • Force 2: 30 N
  • Force 3: 25 N
  • Force 4: 10 N
  • Force 5: 40 N
  • Force 6: (not given, but we can assume it to be 0 N for this calculation)

Breaking Down the Forces

In a regular hexagon, the angles between adjacent sides are 120 degrees. This means that each force can be represented as a vector in a two-dimensional plane. We can resolve each force into its horizontal (x) and vertical (y) components using trigonometric functions.

Calculating Components

Let's assume that the first side of the hexagon is aligned along the positive x-axis. The forces can be resolved as follows:

  • Force 1 (20 N):
    • Fx1 = 20 N
    • Fy1 = 0 N
  • Force 2 (30 N):
    • Fx2 = 30 N * cos(120°) = -15 N
    • Fy2 = 30 N * sin(120°) = 25.98 N
  • Force 3 (25 N):
    • Fx3 = 25 N * cos(240°) = -12.5 N
    • Fy3 = 25 N * sin(240°) = -21.65 N
  • Force 4 (10 N):
    • Fx4 = 10 N * cos(300°) = 5 N
    • Fy4 = 10 N * sin(300°) = -8.66 N
  • Force 5 (40 N):
    • Fx5 = 40 N * cos(0°) = 40 N
    • Fy5 = 40 N * sin(0°) = 0 N

Summing the Components

Now, we can sum all the x and y components to find the resultant force:

Resultant in the x-direction

Rx = Fx1 + Fx2 + Fx3 + Fx4 + Fx5

Rx = 20 N - 15 N - 12.5 N + 5 N + 40 N = 37.5 N

Resultant in the y-direction

Ry = Fy1 + Fy2 + Fy3 + Fy4 + Fy5

Ry = 0 N + 25.98 N - 21.65 N - 8.66 N + 0 N = -4.33 N

Calculating the Magnitude and Direction

The magnitude of the resultant force can be found using the Pythagorean theorem:

|R| = √(Rx² + Ry²)

|R| = √(37.5² + (-4.33)²) ≈ √(1406.25 + 18.75) ≈ √(1425) ≈ 37.7 N

Finding the Direction

The direction (angle θ) of the resultant can be calculated using the arctangent function:

θ = tan⁻¹(Ry/Rx)

θ = tan⁻¹(-4.33/37.5) ≈ -6.5°

Final Result

The magnitude of the resultant force is approximately 37.7 N, and it acts at an angle of about -6.5° from the positive x-axis, indicating that it is slightly below the x-axis. This analysis shows how vector addition can be applied to forces acting in different directions, even in a geometric shape like a hexagon.