Question

Two vectors have magnitude 5 unit and 10 unit. The magnitude of the resultant vector of these two vectors can never be:
1. 4 units
2. 5 units
3. 8 units
4. 12 units

Answer 1

Correct Answer - Option 1 : 4 units

CONCEPT: 

The Resultant of two vectors is given by:

R2 = (A2 + B2 + 2AB cosθ) 

where R is the resultant vector, A and B are the two vectors, and θ is the angle between two vectors.​

Maximum value of R = A + B when θ = 0° 

Minimum value of R = A - B when θ = 180° 

CALCULATION:

Given that Two vectors are 5 units and 10 units

The maximum value of the resultant R = A + B = 10 + 5 = 15 units

The minimum value of the resultant R = A - B = 10 - 5 = 5 units

• The resultant vector can be between 5 to 15 units.
• So the result could not be 4 units.
• Hence the correct answer is option 1.