From Mechanics

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Revision as of 17:41, 16 May 2010

The sum of the forces is zero as the body has constant velocity. This means the sum of the forces in all directions is zero.

Resolving horisontally,

\displaystyle \begin{align} & \to :\quad 42+P-Q\cos {{45}^{\circ }}=0 \\ & \\ \end{align}

Resolving vertically,

\displaystyle \begin{align} & \uparrow :\quad 25+42\sin {{30}^{\circ }}-Q\cos {{45}^{\circ }}=0 \\ & \\ & Q=\frac{25+42\sin {{30}^{\circ }}}{\cos {{45}^{\circ }}}=\frac{46}{0\textrm{.}707}=65\textrm{.}1 \ \text{N} \\ \end{align}