# Answer to Question #16966 in Mechanics | Relativity for nidhi

Question #16966

two forces of magnitude 8N and 15N respectively act at a point.if the force is 17N,the angle between the forces has to be

1.60

2.45

3.90

4.30

1.60

2.45

3.90

4.30

Expert's answer

Let's write down the formula for the magnitude of the resultant:

R = √( a² + b² + 2*a*b*cos(α) ), (1)

where α is the angle between the forces. Therefore,

(1) ==> α = arccos (R² - a² - b²) / (2*a*b) =

= arccos (17² - 8² - 15²) / (2*8*15) =

= arccos 0 = π/2.

So, right answer is 3.90.

R = √( a² + b² + 2*a*b*cos(α) ), (1)

where α is the angle between the forces. Therefore,

(1) ==> α = arccos (R² - a² - b²) / (2*a*b) =

= arccos (17² - 8² - 15²) / (2*8*15) =

= arccos 0 = π/2.

So, right answer is 3.90.

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