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another physics doubts

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astarmathsandphysics:
Will when i get home.

helllife:

--- Quote from: astarmathsandphysics on November 15, 2009, 02:55:15 pm ---Will when i get home.

--- End quote ---

okay, no problem, take your time!!

astarmathsandphysics:
I post to questions like this to make it easy to find the post when i get home.

astarmathsandphysics:
A fighter plane flying horizontally at an altitude of 1.5km with a speed of 720km/h passes directly overhead an anti-aircraft gun. At what angle from the vertical should the gun be fired for the shell with muzzle speed 60m/s to hit the plane?

the answe is 19.47', can u show the workings??
Coordinate of plane are(200t,1500)
coordinates of shell are (60tsinx, 60tcosx-0.5*9.8t^2)
hence
1500=60tcosx-0.5*9.8t^2 (1)
200t=60tsinx (2)

Are you sure the speed of the shell is 60m/s? It will never catch the plane?

I think it is 600
if it is then (2) becomes 200t=600tsinx so sinx=1/3 so x=sin^-1(1/3)=19.47 degrees

helllife:
thank you...... i understood.......i think the speed should be 600m/s...

so basically, we are using pythorus theorum...right?
 
can use write in this way,
cosx = 200/600
x=70.52
to find the angle from vertical......
y= 90-70.52
  = 19.48?

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