Originally Posted by **Christianna** The only second law equation I know is F=ma, which gives me the net force. Is there a way to calculate it with the acceleration and slope? I haven't seen anything like this question in any of the textbook examples. I'm taking an online course (bad decision) and basically have to teach myself out of the textbook. Does it have something to do with calculating the amount of force needed to move the block with the static friction coefficient? I've only learned how to calculate friction forces with normal force which I don't know how to get without the horizontal component of the push force. |

Don't worry, there's plenty of help for those with a serious interest in the subject.

Yes Newton's second law (N2) is Force = mass times acceleration

I assume you have covered resolution of forces so you know how to resolve forces parallel to and perpendicular to the slope.

A pity you have used F for the horizontal force, not H.

So I will use Z for the frictional force, and R for the reaction.

The block is in equilibrium perpendicular to the slope (or if you like has zero acceleration perpendicular to the slope) so resolving perp to the slope

R = Zsin25 + Mgcos25 (or M times zero = Zsin25 + Mgcos25 - R)

The block is moving and not in equilibrium parallel to the slope so applying N2

Ma = Fcos25 -Mgsin25 - Z

Finally we have the relation that Z = the coefficient of dynamic friction x R.

Putting these three equations together allows us to solve for F.