Projectile magnitude and angle question

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Homework Help Overview

The discussion revolves around a projectile motion problem in AP physics, specifically focusing on determining the magnitude and angle of the initial velocity of a projectile launched from a height of 1.6 m, with a hang time of 4.5 s and a horizontal distance of 48 m. Participants are exploring the implications of the non-zero initial height on the calculations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the x-component of the initial velocity using a kinematic equation but expresses uncertainty about finding the y-component. Some participants question the correctness of the method used for the x-component and suggest reconsidering the direction of acceleration. Others provide guidance on the equations that could be used to find the initial y-component based on the hang time and initial height.

Discussion Status

The discussion is active, with participants providing feedback on the calculations and suggesting further steps to find the initial y-component of the velocity. There is acknowledgment of the correct x-component, and participants are collaboratively exploring the necessary equations to progress in solving the problem.

Contextual Notes

Participants are working under the constraints of the problem as stated, including the specific values for time, horizontal distance, and initial height. There is an emphasis on understanding the effects of the non-zero initial height on the projectile's motion.

NeoSlayer888
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Hello, I am currently taking AP physics and require some assistance with a problem. I have to find the magnitude and angle of the original velocity of a projectile, normally this would be no problem for me but the original height is not zero which is giving me some problems.

My givens are:
t= 4.5s
dx= 45m
h= 1.6m

I believe I can get the x component with:
delta x=vox t +1/2gt**2
45m=vox(4.5s) + 4.905(4.5s**2)
so vox= .4334

If I did the above correctly all I would need now would be the y component, the problem is I have no idea on how to find it.

Any assistance would be greatly appreciated.
 
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Please post the exact question as it appears in your book. Your method of finding the x velocity is wrong. Think, what direction is the acceleration?
 
The problem is:
A football player punts the football so that it will have a "hang time" (time of flight) of 4.5 s and land 48 m away. If the ball leaves the player's foot 160 cm above the ground, what initial velocity must the ball have?

Also, yes I did do the x component wrong. I think it should be:
delta x=vxt + xo
48=vx4.5 + 0
so vx= 10.66
 
Yup, you got the correct x-component. v_x = 10.66 m / s.
Now your goal is to find the initial y-component.
First, you know that the ball has a 'hang time' of 4.5 s, and it's 1.6 m above the ground. What equation should you use to find out the initial velocity with the given information?
Note that the ball has an acceleration of -g (downward).
So you can use:
[tex]x = x_0 + v_it + \frac{1}{2}at ^ 2[/tex]
to find v_i (the initial y-component).
x_0 is the ball's initial position (or height), ie: 1.6 m.
When the ball hits the ground, x = 0.
With the x-component and the y-component, can you find out the ball's initial velocity?
Viet Dao,
 
Last edited:

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