Yoyo asked in Science & MathematicsPhysics · 1 month ago

confused ?

why the x component in the picture of the car is ( sin ) and in the second picture “ free body diagram “ the x component is ( cos ) . 

is it always the x component  (cos ), is not ? 

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4 Answers

  • 1 month ago

    It depends which angle you use. Try the video in the link which explains resolving vectors from basics.

  • Dixon
    Lv 7
    1 month ago

    The angle is with respect to vertical in one diagram and horizontal in the other.

  • oubaas
    Lv 7
    1 month ago

    Pls have a look to the sketch shown below :

    The gravitational force parallel to the incline that makes the body sliding down is GF = m*g*sin Θ and  it is the force you have to overcome if you want to move the body up a frictionless incline .

    If there is friction , then the friction force FF, parallel to the incline and having the same versus of GF, will be equal to m*g*cos Θ*μ , so the total force F to be applied will be equal to :

    F = GF+FF = m*g*sin Θ +  m*g*cos Θ*μ = m*g*(sin Θ + cos Θ*μ ) 

    If the body is kept at rest by the only friction , then it must be :

    m*g*sin Θ = m*g*cos Θ*μ

    m*g cancels 

    μ = sin Θ / cos Θ = tan Θ

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  • 1 month ago

    Remember cos30 = sin60  and sin30 = cos60 

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