Recent content by furor celtica

thanks

Homework Statement A small smooth ring R of mass 0.1 kg is threaded on a light string. The ends of the string are fastened to two fixed points A and B. The ring hangs in equilibrium with the part AR of the string inclined at 40° to the horizontal, as shown in the diagram. Show that the part...

A small smooth ring R of mass 0.1 kg is threaded on a light string. The ends of the string are fastened to two fixed points A and B. The ring hangs in equilibrium with the part AR of the string inclined at 40° to the horizontal, as shown in the diagram. Show that the part RB of the string is...

gnaaargh its your fault being all mysterious. i really don't see it man, I've been going over this question for ages so I'm probably missing the really obvious, but could you just be a bit clearer?

take O and A as the same point?

vector BC is perpendicular to the position vector of A

thanks, but I'm firstly stuck on a.!

really not seeing it! what do you mean by 'suitable origin'? And what is the end result I'm looking for, exactly?

haha ok i feel silly now. I'm still stuck on a., though.

how should i solve the first task then?

Prove that, if (c - b).a = 0 and (c - a).b = 0, then (b - a).c = 0. Show that this can be used to prove the following geometric results: a. The lines through the vertices of a triangle ABC perpendicular to the opposite sides meet in a point. b. If the tetrahedron OABC has two pairs of...

Prove that, if (c - b).a = 0 and (c - a).b = 0, then (b - a).c = 0. Show that this can be used to prove the following geometric results: a. The lines through the vertices of a triangle ABC perpendicular to the opposite sides meet in a point. b. If the tetrahedron OABC has two pairs of...

yes! I'm not sure how to sketch a three-dimensional vector at all, especially if the points are not collinear.

Alright so here’s my work on b. : We have 3BF = FD, f = BF + b And since we know b, all we need is BF to find f position vector of F BF + FD = BD => 4BF = d – b = 4i – 4j – 4k => BF = i – j – k => f = (1+1)i + (3-1)j + (2-1)k = 2i + 2j + k Now I’m aware that my error lies in assuming...

Homework Statement First of all, sorry if this isn't the right place to post this. Four points A, B,C and D have coordinates (0, 1, -2), (1, 3, 2), (4, 3, 4) and (5, -1, -2) respectively. Find the position vectors of a. The mid-point E of AC b. The point F on BC such that BF/FD = 1/3 Use...