Find the magnitude of the resultant force and the angle it makes with the positive x-axis. (Let a = 28 lb and b = 12 lb. Round your answers to one decimal place.)
a = 45 degree positive on x & y axis.
b = 30 degree below x-axis. I guess negative on y & x.

Respuesta :

Answer:

Magnitude of R = 16.7 lb

Angle = 55.7°

Step-by-step explanation:

Given:

a = 28 lb

b = 12 lb

a = 45 degree positive on x & y axis.

b = 30 degree below x-axis. negative on y & x.

Resolving the two forces to vector form, we have

a = (28cos45)i + (28sin45)j

b = (-12cos30)i + (-12sin30)j

The resultant force vector R = a +b

R = (28cos45 - 12cos30)i + (28sin45 - 12sin30)j

R = 9.41i + 13.80j

Magnitude of R = √(9.41^2 + 13.80^2) = 16.7 lb

Angle = taninverse (13.80/9.41) = 55.7°

To determine the magnitude of the resultant force, the two given forces have to be resolved as vectos. In the question, the magnitude of the resultant force is 39.7 N and makes an angle of [tex]49.5^{o}[/tex] with the x-axis.

The two given forces are vectors, thus they have to be resolved horizontally and vertically so as to determine their resultant.

So that:

  Horizontal component = F Cos θ

   Vertical component = F Sinθ

Thus, given that: a = 28 lb at [tex]45^{o}[/tex] on x & y axis, and b = 12 lb at [tex]30^{o}[/tex] below x-axis.

i. Resolving the vector horizontally, we have:

horizontal component = 28 Cos[tex]45^{o}[/tex]  + 12 Cos [tex]30^{o}[/tex]

                                     = 19.80 + 10.39

horizontal component, x  = 30.19

ii. Resolving the vectors vertically, we have:

vertical component = 28 Sin [tex]45^{o}[/tex] + 12 Sin [tex]30^{o}[/tex]

                                = 19.80 + 6.0

vertical component, y  = 25.80

a. Magnitude of the resultant force, |R| = [tex]\sqrt{x^{2} + y^{2} }[/tex]

                = [tex]\sqrt{(30.19)^{2} + (25.80)^{2} }[/tex]

                   = 39.7124

|R|     = 39.7 Newtons

b. The angle that the resultant makes with the positive x-axis can be determined by:

Tan θ = [tex]\frac{x}{y}[/tex]

θ =  [tex]Tan^{-1}[/tex] [tex]\frac{30.19}{25.80}[/tex]

  = 49.4832

θ = [tex]49.5^{o}[/tex]

Therefore, the magnitude of the resultant force is 39.7 N and makes an angle of [tex]49.5^{o}[/tex] with the x-axis.

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