Question

Which of the following set of magnitudes of three forces can't make zero resultant all are coplanar? 1) 2,11,5 2) 8,6,6. 3) 3,5,4 4) 12,16,18​

Answer 1

Answer:

None can make only option C can make because it is Pythagorean triplet so forms a closed right angled triangle so hence its resultant is zero.

Explanation:

Answer 2

Answer:

THE ANSWER TO THIS QUESTION IS OPTION 1)2,11,5

Explanation:

• So the concept needed for this question is vector law addition of forces.

• In order for the vector sum to become zero it should follow the triangular law of vector addition which states that the three vectors have to form a triangle in order to cancel out and give a resultant of zero.

• Now from observation we can get to know that the triplet 3,4,5 is a Pythagorean triplet and hence they form the sides of a right angled triangle.

• Option 2),4) follows triangle inequality hence these form a sides of triangle

• When we look vectors(forces) of magnitudes as in other option 1) they don't form the sides of a triangle as they don't follow the triangle inequality.

                                      TRIANGULAR INEQUALITY

                              a+b>c    where a ,b, c are sides of the triangles

  Now using this inequality in case

1.              2+5>11 is false

2.              8+6>6 is true

                6+6>8 is true

3.            Pythagorean triplet also follows inequality

4.            12+16>18 is true

              12+18>16 is true

              16+18>12 is also true