Is Gravity Always Negatively Affecting a Ball?

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The discussion revolves around the physics of motion, specifically the effects of gravity and the calculations of velocity and acceleration for a ball in motion. Participants clarify that gravity exerts a constant negative force, and they explore the mathematical derivation of velocity and acceleration using derivatives of position equations. The conversation also touches on the use of unit vectors in representing velocity and acceleration vectors, emphasizing the importance of including these in final expressions. Additionally, they discuss the trajectory of the object's motion, concluding that it resembles a circular path rather than a simple sine curve. The overall focus is on understanding motion through mathematical principles and conventions in physics.
  • #51
I just started this chapter and do not understand a lot of this...like the cartesian coordinate system
 
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  • #52
x=-(5.00m) sin \omega t

y=(4.00m)-(5.00m)cos \omega t

We could square the x expression so

x^2=(25.00m) sin^2 \omega t

then apply the pythogoras identities

x^2=(25.00m) (1 - cos^2 \omega t)

x^2=(25.00m) - (25.00m) cos^2 \omega t

(25.00m) - x^2 = (25.00m) cos^2 \omega t

\frac{(25.00m) - x^2}{(25.00m)} = cos^2 \omega t

\sqrt{\frac{(25.00m) - x^2}{(25.00m)}} = cos \omega t

Substitute in the other

y=(4.00m)-(5.00m)\sqrt{\frac{(25.00m) - x^2}{(25.00m)}}

Evaluate this graph, i think it will be better.
 
  • #53
Well i graphed it in my calculator, i guess i was wrong, looks like a circle, i was thinking about it too, looked like an elipse expression for a polar coordinate, I'm not sure about the path. In the cartesian it forms an arc.
 
  • #54
I'm trying to understand what you did, is this relating my first problem or my second problem?
 
  • #55
I asked a friend (mathematician) he says it will form a cardiode in a polar, and half a circle in cartesian, that should be the path, i don't know how to explain it to you.. but i think the question asked maybe requires a simpler solution, and i must had misunderstood it.
 
  • #56
wow, that is WAY beyond me. What question were you trying to answer?
 
  • #57
The trajectory, if you want put an asterisk next to it, see what your teacher says.
 
  • #58
This is all I did:

x=-(5.00m) sin ωt
x=-(5.00m) sin ω(0)
x=0m

y=(4.00m) – (5.00m) cos ωt
y=(4.00m) – (5.00m) cos ω(0)
y= (4.00m) – (5.00m) = 1.00m

The path of the object would represent a sine cure. The x position would start at zero while the y position would start at 1m.
 
  • #59
Its path is half a circle actually... Like my friend said. I was wrong about the sine curve.
 
  • #60
so it's like a parabolic arc? Not quite sure how I could describe this.

"The ball will bounce like a parabolic arc"?
 
  • #61
Yea, it seems.
 
  • #62
Could you check if I did this correct...

The componet for velocity is x’= -(5.00m) ω cos ωt and y’= (5.00m) ω sin ωt
At t=0 seconds, x’= -(5.00m) ω and y’=0m/s
The componet for acceleration is x’’=(5.00m)ω^2 sin ωt and y’’= (5.00m) ω^2 cos ωt
At t=0 seconds, x’’=0m/s^2 and y’’=(5.00m)ω^2
 
  • #63
Looks ok to me.
 
  • #64
I wasnt sure if the omega symbol needed to be included in the answer or not, just checking
 
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