ATAR Notes: Forum

VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: Martoman on September 06, 2010, 04:09:16 pm

Title: resultant?
Post by: Martoman on September 06, 2010, 04:09:16 pm: PROB 1) I think their answer of $10\sqrt{7}$ is wrong. I create a triangle of sides 20,30 and the angle between them being 150. Using cosine rule yeilds my answer, which is not theirs :S

The second one can be completed with lami's theorm getting 0.3... but when resolving with forces I seem to fail... so could someone resolve the forces for me :smitten:
Title: Re: resultant?
Post by: kamil9876 on September 06, 2010, 06:22:10 pm: I'm assuming that in 2 you are in static equilibrium.

you know that angle between the dotted line and the rope is 60deg.

Let $T$ be the tension in the rope, then we know that:

$Tsin(\pi/3)=0.5g$

Using this, you can now find $Tcos(\pi/3)$ which is in fact equal to $P$ .
Title: Re: resultant?
Post by: theuncle on September 06, 2010, 10:13:05 pm: Quote from: kamil9876 on September 06, 2010, 06:22:10 pm
$Tsin(\pi/3)=0.5g$
Why 0.5g and not just g?

EDIT:
DUH! 0.5kg x g