Posted by Physics on .
My question is
A block is given an intial speed of 4.0 s^1 m up the 22 degree plane
How far up the plane will it go?
How much time elapses before it returns to its starting point? Ignore friction.
Ok my teacher said use this to find acceleration a = g sin è and then I know where to go from there but were does this formula come from?

Physics 
bobpursley,
g is downward. Since the block cannot slid downward, it can only slide along the surface. So the component of g in the direction of the surface is gsin22.
http://www.lastufka.net/lab/cars/why/ramps.gif
Notice the two components: down the ramp, mgsintheta, and the other component of g, perpendicular, mgcosTheta. That perpendicular force assists friction, but in this case we are ignoring it.