Kinematics - trajectory formula

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SUMMARY

The discussion focuses on deriving the trajectory formula for projectile motion using trigonometric identities. The key relationship established is between the variables x and y, expressed as ##\frac{y}{a} = 1 - 2\sin^2(\omega t)## and ##\frac{x^2}{a^2} = \sin^2(\omega t)##. The final equation derived is ##\frac{2x^2}{a^2} + \frac{y}{a} = 1##, leading to the conclusion that the trajectory is a parabolic curve represented by ##y = -\frac{2}{a}x^2 + a##. This confirms the expected shape of the projectile's path.

PREREQUISITES
  • Understanding of trigonometric identities, particularly sine and cosine functions.
  • Familiarity with the concepts of projectile motion in physics.
  • Knowledge of parabolic equations and their graphical representation.
  • Basic algebra skills for manipulating equations.
NEXT STEPS
  • Study the derivation of projectile motion equations in physics.
  • Learn about the properties of parabolas and their applications in physics.
  • Explore advanced trigonometric identities and their uses in solving equations.
  • Investigate the impact of varying parameters (like angle and initial velocity) on projectile trajectories.
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Students studying physics, particularly those focusing on kinematics, as well as educators and anyone interested in understanding the mathematical foundations of projectile motion.

quas
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Homework Statement


given :
1409395.jpg
i need to find the trajectory formula

Homework Equations


i'm not sure if to use :
6687766.jpg


The Attempt at a Solution


6325967.jpg
[/B]
I tried different options with the trigonometric identities that I have written before:
8541126.jpg

thanks
 
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quas said:

The Attempt at a Solution


6325967.jpg
[/B]

If ##x## and ##y## are as above, can you not find a simple relationship? You've already quoted the relevant trig identity somewhere.
 
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PeroK said:
If ##x## and ##y## are as above, can you not find a simple relationship? You've already quoted the relevant trig identity somewhere.

do you mean?

9133966.jpg
 
quas said:
do you mean?

9133966.jpg

No, I meant:

##\frac{y}{a} = \cos(2 \omega t) =## something to do with ##\sin(\omega t) =## something to do with ##\frac{x}{a}##

You're terribly over-complicating this.
 
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PeroK said:
No, I meant:

##\frac{y}{a} = \cos(2 \omega t) =## something to do with ##\sin(\omega t) =## something to do with ##\frac{x}{a}##

You're terribly over-complicating this.

Ok I can write ##\frac{y}{a} =1-2sin^2(\omega t) ##, also to ## \frac{x^2}{a^2}\ = sin^2(\omega t) ## and then insert ## sin^2(\omega t) ##
to the equation ##\frac{y}{a} =1-2sin^2(\omega t) ## . would it be correct?
 
quas said:
Ok I can write ##\frac{y}{a} =1-2sin^2(\omega t) ##, also to ## \frac{x^2}{a^2}\ = sin^2(\omega t) ## and then insert ## sin^2(\omega t) ##
to the equation ##\frac{y}{a} =1-2sin^2(\omega t) ## . would it be correct?

You seem to have a mental block about replacing ##\sin(\omega t) ## by ##\frac{x}{a}##.
 
PeroK said:
You seem to have a mental block about replacing ##\sin(\omega t) ## by ##\frac{x}{a}##.
first of all thanks for your help it's not taken for granted
Last try:
in the end I will get : ## \frac{2x^2}{a^2}+ \frac{y}{a}=1 ## then : ## y= - \frac{2}{a}x^2+a ## and that's parabola figure . right ?
 
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quas said:
first of all thanks for your help it's not taken for granted
Last try:
in the end I will get : ## \frac{2x^2}{a^2}+ \frac{y}{a}=1 ## then : ## y= - \frac{2}{a}x^2+a ## and that's parabola figure . right ?

It is!
 
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