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The Inclined Plane motion problem is a classic problem in demonstrating the laws of motion. It necessitates the use of force vectors. It also requires integration of the acceleration induced by the force vector sum, to obtain the block displacement, `s`. Here we will use shorten the phrase "inclined plane" to the term "ramp". The gravity force component that is perpendicular to the ramp surface results in a sliding friction force that reduces the impact of the gravity force component that is parallel to the ramp. For small ramp angles the friction force can be large enough that the block does not start to slide.
This page shows how the parallel and perpendicular force vectors sum together to be equivalent to the downward gravity force vector, `mg`. To sum two vectors graphically, we place the tail of an arrow representing the second vector at the tip of the arrow representing the first vector. Here the parallel and perpendicular force vectors are blue and they add up to the red downward gravity force vector as they must.
The forces on the block are:
`F_("parallel")=mg sin theta \ \ \ \("gravity force along ramp")`
`F_("perpendicular")=mg cos theta \ \ \ \("gravity force perpendicular to ramp")`
`mu=C_("friction") mgcos theta\ \ \ \ \("friction force")`
The equations of motion are:
`m (d^2s)/dt^2=mg sin theta-C_("friction") mgcos theta\ \ \ \ ("equation of motion")`
`s=("gt"^2)/2(sin theta-C_("friction")cos theta)) \ \ \ \ \("solution for s")`