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Find the resultant of the three vectors OA,OB and OC shown in figure .Radius of the circle is R . please give more explanation with solution

Vaibhav , 7 Years ago
Grade 12
anser 2 Answers
Saurabh Koranglekar

Last Activity: 6 Years ago

To solve this problem, we need to find the resultant of three vectors OA, OB, and OC that are given as position vectors on a circle of radius R.

### Step 1: Understanding the Problem
- The three vectors originate from the center of the circle and point towards points A, B, and C on the circumference.
- The angle between the vectors is not explicitly given, but we assume they are symmetrically placed, meaning they form angles of 120 with each other.

### Step 2: Representing Vectors in Component Form
Since the vectors are directed radially outward from the center and positioned symmetrically, we express them using unit vectors.

#### Vector Representation:
Let’s assume:
- OA lies along the positive x-axis.
- OB and OC make angles of 120 and 240 respectively with the x-axis.

Using unit vectors:
- OA=Ri^
- OB=R(cos120i^+sin120j^)
- OC=R(cos240i^+sin240j^)

Using trigonometric values:
- cos120=12, sin120=32
- cos240=12, sin240=32

Thus:
- OB=R(12i^+32j^)
- OC=R(12i^32j^)

### Step 3: Finding the Resultant
The resultant vector R is given by:
R=OA+OB+OC

#### x-component:
Rx=R+R(12)+R(12)
Rx=RR2R2=RR=0

#### y-component:
Ry=0+R(32)+R(32)
Ry=R32R32=0

### Step 4: Magnitude of Resultant
|R|=Rx2+Ry2=02+02=0

### Conclusion:
The resultant of the three vectors is zero. This happens because the three vectors are symmetrically arranged around the center, leading to perfect cancellation of their components. Hence, the system is in equilibrium.

**Final Answer:** The resultant of the three vectors is **zero**.

Aayush Sharma

Last Activity: 4 Years ago

we can simply find the component of the vector :
for OA - Rcos0=R ( as cos 0 = 1 ) 
for OB - Rcos45=R/√2 ( as cos 45 = 1/√2 )
for OC - Rcos45=R/√2 ( as cos 45 = 1/√2 )
Adding all we get - R/√2 + R/√2 + R = 2R/√2 + R , which on further simplification gives √2R + R = 
R(√2+1) , hence the required answer.
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