1. ## horizontal forces

the diagram (attached) shows three horizontal forces acting on a mass of 4kg. Given that the mass moves in the direction of the dotted line, show that theta=30 and find the magnitude of the acceleration.

i usually dont say this, but for once i actually dont know where to start. i have no problem with vertical stuff and weights and all but here i dont get where the weight comes in or even how the forces are interrelated.

2. Originally Posted by furor celtica
the diagram (attached) shows three horizontal forces acting on a mass of 4kg. Given that the mass moves in the direction of the dotted line, show that theta=30 and find the magnitude of the acceleration.

i usually dont say this, but for once i actually dont know where to start. i have no problem with vertical stuff and weights and all but here i dont get where the weight comes in or even how the forces are interrelated.
hi

Firstly , resolve the forces into their vertical and horizontal components respectively . Also , taking upwards and right as positive .

Vertical : 8 sin Θ -4

horizontal : 8 cos Θ -2

Since the resultant force (F') is horizontal , the vertical component would be 0 , 8 sin Θ -4 =0 , Θ = 30 degree .

F'=8 cos 30 -2 =4.93 N

F=ma , 4.93=4a

a=1.233 m/s^2