Answer
When a 50 N horizontal force and a 40 N force at 30° or 60° to the horizontal act on an object, the resultant forces are approximately 87 N and 78.1 N, respectively.
Solution
To determine the resultant force when two forces act on an object using a graphical method, we'll break down the process step-by-step. Although we can't draw the vectors here, we'll use numerical calculations to simulate the graphical approach based on the given scale of \(1 \, \text{mm} : 1 \, \text{N}\).
### Given:
1. **Force \( \mathbf{F}_1 \):** 50 N (horizontal)
2. **Force \( \mathbf{F}_2 \):** 40 N at an angle to the horizontal
- **Case 1:** \(30^\circ\) to the horizontal
- **Case 2:** \(60^\circ\) to the horizontal
### Objective:
Find the magnitude of the **resultant force \( \mathbf{R} \)** for both cases.
### Method:
We'll use the **Law of Cosines** to calculate the magnitude of the resultant force when two vectors are at a certain angle to each other.
\[
R = \sqrt{F_1^2 + F_2^2 + 2 F_1 F_2 \cos(\theta)}
\]
where:
- \( R \) = magnitude of the resultant force
- \( F_1 \) and \( F_2 \) = magnitudes of the two forces
- \( \theta \) = angle between the two forces
### Calculations:
#### **Case 1: \(40 \, \text{N}\) at \(30^\circ\) to the horizontal**
1. **Identify the Angle Between Forces:**
- \( \theta = 30^\circ \)
2. **Apply the Law of Cosines:**
\[
R = \sqrt{50^2 + 40^2 + 2 \times 50 \times 40 \times \cos(30^\circ)}
\]
\[
\cos(30^\circ) = \frac{\sqrt{3}}{2} \approx 0.8660
\]
\[
R = \sqrt{2500 + 1600 + 4000 \times 0.8660}
\]
\[
R = \sqrt{2500 + 1600 + 3464}
\]
\[
R = \sqrt{7564} \approx 87 \, \text{N}
\]
#### **Case 2: \(40 \, \text{N}\) at \(60^\circ\) to the horizontal**
1. **Identify the Angle Between Forces:**
- \( \theta = 60^\circ \)
2. **Apply the Law of Cosines:**
\[
R = \sqrt{50^2 + 40^2 + 2 \times 50 \times 40 \times \cos(60^\circ)}
\]
\[
\cos(60^\circ) = 0.5
\]
\[
R = \sqrt{2500 + 1600 + 4000 \times 0.5}
\]
\[
R = \sqrt{2500 + 1600 + 2000}
\]
\[
R = \sqrt{6100} \approx 78.1 \, \text{N}
\]
### Summary of Results:
- **When the 40 N force is inclined at \(30^\circ\):**
- **Resultant Force \( R \approx 87 \, \text{N} \)**
- **When the 40 N force is inclined at \(60^\circ\):**
- **Resultant Force \( R \approx 78.1 \, \text{N} \)**
### Graphical Interpretation:
If you were to draw this graphically:
1. **Scale:** \(1 \, \text{mm} = 1 \, \text{N}\)
2. **Draw \( \mathbf{F}_1 \):** Draw a horizontal line 50 mm long.
3. **Draw \( \mathbf{F}_2 \):** From the end of \( \mathbf{F}_1 \), draw a line at the specified angle (30° or 60°) 40 mm long.
4. **Resultant \( \mathbf{R} \):** Draw a line from the origin (start of \( \mathbf{F}_1 \)) to the end of \( \mathbf{F}_2 \). The length of this line represents the magnitude of the resultant force.
Using this method with accurate measurements will give you the resultant forces calculated above.
Reviewed and approved by the UpStudy tutoring team
Explain
Simplify this solution