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Could someone please help me on this question i've totally lost all understanding of vectors lol
A particle P is moving with a constant velocity (3i+2j)m-1. At time t=6s, P is at the point with position vector (-4i-7j)m. Find the distance of P from the origin at time t=2s.
I'm confused, maybe look at mymaths... it might help
I think I've solved it but you will have to check
First I used the equation r = ro + vt (position vector = original position + (velocity x time)to find the original position
so -4i - 7j = ro + 6(3i + 2j)
-4i - 7j = ro + 18i + 12j
ro = -22i - 19j
Then i used the same equation to find the position at t=2
r = -22i - 19j + 2(3i + 2j)
r = -22i - 19j + 6i + 4j
r = -16i -15j
This is the distance from the origin in vectors so I used pythagoras to find the actual distance from the origin
a2 + b2 = c2
(-16)2 + (-15)2 = c2
c2 = 481
c = 21.9317122
distance from the origin at t=2 is 22m (2 significant figures)
Hope that helps :-)
Are you doing edexcel? x
wow! Long workings man!! lol Well done!! :D
Is it right? x
yupo doing edexcel......................(checks question)....... ans is 17m http://www.kingsleyschoolbideford.co.uk/Images-(1)/SeniorSchool/Maths-PDFS/M1_MS_20100608.aspx
teacher told me it was position vector at 6s + velocity(-4) <- -4 comes from 6-2
But Thanks a lot anyway i really couldn't get my head around the question I despise vectors!!
actually seeing as we are the topic of Mechanics does anyone know how to decide which way the resolving forces go when u are working it out? it drives me insane i always get my signs the wrong way! anyone?.....
I know I hate vectors too!