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A projectile is fired with an initial speed of 37.0 m/s at an angle of 44.9 ∘ above the horizontal on a long flat firing range. Determine the maximum height reached by the projectile.

 Oct 1, 2015
 #1
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First of all, get the VERTICAL component of the initial velocity:

V = 37m/s (sin(44.9) = 26.117 m/s

When the Vertical velocity equals ZERO, the projectile has reached its highest point (apex)

since v= vo + at     (vo = origianl velocity     a = acceleration of gravity = -9.80 m /sec^2   t = time)

ZERO=  26.117 + (-9.80 t)

Solving for t

-26.117 = -9.8 t

26.117/9.8 = t = 2.665 seconds

 

NOW,  use the position equation  pf = po + vt +1/2at^2   pf=Final position (max height...apex)

po = 0

so:

pf = 26.117 (2.665) + 1/2 (-9.8)(2.665)^2   =  69.60 + (-3.48) = 66.1 m   max height

 Oct 2, 2015
 #2
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The vertical displacement is given by:

 

h = v(sin theta)t + 1/2 (-9.8) t^2

 

And  h'  is the vertical velocity at any time.......this is 0 at the max ht.

 

And h'  =   vsin(theta) - 9/8t  =  37sin(44.9)  - 9.8t   ...... set to 0

 

37*sin(44.9) = 9.8t

 

37*sin(44.9)/ 9.8 = t =  2.665 s

 

And putting this back into the position function, the max ht. =

 

h(2.665) =  about 34.8 m

 

Here's the graph :  https://www.desmos.com/calculator/smv5klqan8

 

 

cool cool cool  

 Oct 2, 2015
edited by CPhill  Oct 2, 2015
edited by CPhill  Oct 2, 2015
edited by CPhill  Oct 2, 2015
 #3
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0

First of all, get the VERTICAL component of the initial velocity:

V = 37m/s (sin(44.9) = 26.117 m/s

When the Vertical velocity equals ZERO, the projectile has reached its highest point (apex)

since v= vo + at     (vo = origianl velocity     a = acceleration of gravity = -9.80 m /sec^2   t = time)

ZERO=  26.117 + (-9.80 t)

Solving for t

-26.117 = -9.8 t

26.117/9.8 = t = 2.665 seconds

 

NOW,  use the position equation  pf = po + vt +1/2at^2   pf=Final position (max height...apex)

po = 0

so:

pf = 26.117 (2.665) + 1/2 (-9.8)(2.665)^2   =  69.60 + (-34.8) = 34.8 m  max height

 

 

CORRECTED MATH ERROR IN LAST LINE

 Oct 2, 2015

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