Solving Graphical Resultant Force IGCSE

Here is how you solve Physics questions (Resultant Forces). Student must be able to use graphical method to determien the magnitured of force and also the direction of the force. Step is very simple since this question only requires basic math and some understanding about scale and ratio.

Graphical Method Steps

1. Choose a suitable scale (e.g., 1 cm = 10 N).
2. Draw the first force as a straight line, with its magnitude and direction.
3. From the tip of the first force, draw the second force using the same scale and direction.
4. Continue this process for all forces.
5. Draw a straight line from the starting point to the tip of the last force. This line represents the resultant force.
6. Measure its length (convert to actual magnitude using the scale) and angle (using a protractor).

Examples

Step-by-Step Construction

1. Choose a Suitable Scale

We need to represent the given forces accurately. Let’s use:

$$1\text{ cm}=2\text{ N}$$

Thus, the force vectors will be:

• Horizontal force (8.1 N) → 8.12=4.05\frac{8.1}{2} = 4.0528.1​=4.05 cm
• Vertical force (5.39 N) → 5.392=2.70\frac{5.39}{2} = 2.7025.39​=2.70 cm

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2. Draw the Forces Tip-to-Tail

1. Draw the horizontal force (8.1 N):

   • Start at a point and draw a horizontal line to the right of length 4.05 cm.
   • Mark the endpoint.

2. Draw the vertical force (5.39 N):

   • From the tip of the first vector, draw a vertical line downward of length 2.70 cm.
   • Mark the endpoint.

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3. Draw the Resultant Force

• The resultant force (Tension in the cord) is the vector from the starting point to the tip of the last force.
• Using a ruler, measure the length of this diagonal line.

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4. Measure the Resultant and Angle

• Suppose the measured diagonal length is 4.87 cm.

• Convert back to actual force:

  $$T=4.87\times 2=9.73N$$

• Using a protractor, measure the angle between the resultant force and the ceiling:

  θ≈33.5∘\theta \approx 33.5^\circθ≈33.5∘

 

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