Question

Two forces of magnitude 4n and F act at 120 with each other. If their resultant is at right angles to 4n the value of F is ?

Answer 1

Answer:

I explained in above ,if any doubt msg me

Answer 2

The value of F is 8n.

Given,

Two forces of magnitude 4n and F act at 120 with each other. The resultant is at right angle to 4n.

To Find,

The value of F.

Solution,

Let us assume that R is the resultant of 4n and F.

So,

R = 4n + F

Now, the angle between 4n and f is 120 and the angle between R and 4n is 90.

So, the dot product of R and 4n will be 0

R.(4n) = 0

(4n+F).4n = 0

(4n.4n)+(4n.F) = 0

Now, using the formula of dot product

(4n)²+(4n)(F) cos(120) = 0

16n²-4nF/2 = 0

16n² = 2nF

F = 8n

Hence, the value of F is 8n.

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