Physics

With reference to the force diagrams below:

圖片參考：http://i117.photobucket.com/albums/o61/billy_hywung/April07/Force1.jpg

After resolving the 40N force into 2 compontnes: one opposite to and one perp. to the 80N force as shown in the upper diagram, we can find out the resultant force F as shown in the lower diagram.
By Pyth. thm, the magnitude of F is:
F = √(202 + 45.42)
= 49.6 N (corr. to the nearest 0.1 N)
Also the direction is given by:
tan θ = 20/45.4
θ = 23.8° (corr. to the nearest 0.1°) to the direction of the original 80 N force.
Therefore if there is a mass m kg being acted upon by these forces together in such manner, the acceleration is given by:
a = 49.6/m metre/s2 in the direction of 23.8° to the direction of the original 80 N force.