Question

out of the following pairs of forces the resultant of which cannot be 4 newton​

Answer 1

Answer:

2 Newton and 8 Newton

Explanation:

Let θ be angle b/w two vectors. ∣A∣=2∣B∣=8

their resultant has magnitude

∣R∣= A 2 +B 2 +2ABcosθ

or

∣R∣ 2 =A 2 +B 2 +2ABcosθ

⇒ 32∣R∣ 2 −(90)

=cosθ Now if ∣R∣=4

32

16−70

=cosθ=−1.68, which is not possible.

⇒∣A∣=2 and ∣B∣=8 can never add up to give ∣R∣=4.