Projectile question (1 Viewer)

[conics2008]

Hey I think there is something wrong with this question.

I dont know, maybe im not interpeting it right ??

The question goes like this...


Two particles P and Q are projected simultaneously from the same point with the same speed V in the same vertical plane, their initial directions of motion making angles of alpha and beta respectively with the horizontal. Tkaing g=10 m/s^2

Show that Theta=1/2(180-alpha-beta) where theta is the acute angle the line joining P and Q makes with tthe horizontal, and deduce that theta is a constant.


I did a number of approach to this quesiton that is using angel between two lines and normal geo approach.. but still cant seem to find a away of getting that answers...

is there a problem or is it just me... thanks.. dont show me full working out.. just let me know if there is a problem with the question.. if not can u give me a hint.. or something thanks alot

 

[lolokay]

yeah this can be done. I thought you would be able to do it quite easily, so I guess you must have interpreted the question wrongly. For hints.. remember that tan@ is the gradient of a line, and you need (I think) to use the sum to product identities

and if you can't interpret the question properly, basically it means:
at a point in time, a line is drawn through the positions of P and Q. The acute angle this line makes with the horizontal is theta.

I think maybe the "same speed V in the same vertical plane" might be a bit misleading. I'm not sure what 'vertical plane means' but it sound like it means they have the same vertical velocity. I'm pretty sure it means same overall speed, not the same vertical speed.

 

[conics2008]

lolokay ?

I dont get you!

I still dont understand what the question wants me to find.

 

[lolokay]

2 particles are launched from a point. They have the same speed. P is launched at an angle of alpha, Q at an angle of Beta (measured in the same direction, and also these are in the same vertical plane - which I think means same side of the horizontal that they were projected from, perhaps also implying that the angle is measured in the same direction. can someone clarify this?). They are launched with the same speed. After an amount of time, a line is constructed through P and Q. The acute angle made between this line and the horizontal is theta. The question wants you to "Show that Theta=1/2(180-alpha-beta) where theta is the acute angle the line joining P and Q makes with tthe horizontal, and deduce that theta is a constant." I think the second part of the question is extremely simple and can be simply deduced by looking at what it wants you to show, unless I don't understand what it means.

If this doesn't clarify the question for you.. then can you tell me exactly which bit it is that confuses you.

 

[conics2008]

Hey lolokay, dont worry there was something missing from the quesiton. Dont worry about it, thanks for your input =]

 

[lolokay]

what was missing?

 

[conics2008]

3units get a life, you troll.

I dont need your crappy working out.. do me a favour get a life!