# Search results

1. ### Geometry textbook

Hi I'm starting university in September and wanted to consolidate my current knowledge. I got hold of a nice textbook called 'foundation mathematics' which covers algebra to fairly basic calculus, but was looking for a good one on geometry. Can anyone recommend any decent books (or...
2. ### Work against gravity confusion

Hi I've just started learning work, energy etc and the first question in the book is in the form: An object of mass m is lifted by a tension through a displacement of h. Find the work done on the object. I know that the answer is simply mgh J, there is something that I don't quite get...
3. ### Show that the forces form a couple (algebraic)

Homework Statement A Triangle ABC has sides of length a, b and c labelled according to the usual convention. Forces of magnitude ka, kb and kc act along BC, CA and AB respectively, with the direction given by the order of the letters. By considering the vector sum of the forces, or otherwise...
4. ### Does friction oppose force or motion?

I have always treated friction as 'opposing' force rather than motion, either at its limit or to maintain equilibrium. I have just realised, however, that if an object is at rest on an inclined plane, but is not at limiting equilibrium and you give it a nudge it will accelerate while you apply...
5. ### Friction question, maximum incline

Homework Statement An object of mass 50kg rests on a rough plane incline at an angle alpha to the horizontal. It is supported in this position by a light string parallel to the plane. The string has a breaking strain of 200N and the coefficient of friction between the object and the plane is...
6. ### Moments/torque in relation to laws of motion

I've just started learning about torque, and understand that tau=Fd, but wondered how this relates to F=ma. For example if there is a rod with a pivot in the middle (say a nail), when one end is pushed down, why does the other end move up? Where is the force that causes the end to move up...
7. ### Newtons 3rd law - how can this rope move?

Hi I'm having trouble understanding this situation. Appologies if I posted in the wrong place, this is pretty simple but it's not really a homework question. A horse is attached to a large stone by means of a rope (modelled as light and inextensible). Let the mass of the horse be m and the...