Stuck with this on a practice test.. What do you think?

I reckon D. but I'm wrong.



Two objects (a and b) travel with velocities

Va = 40i + 50j

and

Vb = 75j

Determine the relative velocity Vba
Question 3 answers
a) Vba = 40i + 125j
b) Vba = -40i + 25j
c) Vba = -40i - 125j
d) Vba = 40i - 25j

 

ill go for A.

 

i'll go B.....

my thinking is...Vba...so you put b first...and do it like simultaneous equations...

But I could be wrong.

as in

Vb = 75j
Va=40i+50j

take them away from each other?

-40i + 25j

Never done anything on velocity ever...but thats what Id guess.

 

id go b also

 

I'll go A.

40i+50j+75j=165

40i+125j=165

If both i + j = 1

 

can i change my guess

 

B

 

I don't understand any of it

 

lost me lol

 

B was correct.

That's that done - how did you get to the answer? Punkies I'm not so sure about but could work I guess.

 

Sorry Punkie - I think you are correct with your working too.

Well done.

 

WOOHOO. It was more luck than judgement though.