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Resolving parallel and perpendicular to an inclined plane - DOC

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					   Resolving parallel and perpendicular to an inclined plane including friction.

A block mass m kg on a
rough inclined plane at
angle θ to the horizontal.
R is the normal reaction.             R                P
P is a pull force acting at an                                            P        Psinα
angle α to the plane.
If the block is moving or                          α                        α
                                                                                  Pcosα
tending to move up the              Fr
plane the frictional force Fr                  θ
will act down the plane.
                                          mg
                                                                                θ mgcosθ
                                                                       mg
                     θ                                                            mgsinθ


       If the block is in equilibrium (stationary or moving with const velocity):

       Parallel to slope : P cosα = Fr + mgsinθ

       Perpendicular to slope : R = mgsinθ

       If the block is accelerating up the slope with acceleration a then there will be a
       resultant force parallel to the slope but perpendicular to the slope the forces will
       still balance.

       Parallel to slope “F = ma” : The resultant force F is P cosα – mgsinθ - Fr so
                                     P cosα – mgsinθ - Fr = ma

       Perpendicular to slope :       R = mgsinθ

				
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posted:2/28/2010
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