Finding the x component of position vector

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Homework Help Overview

The discussion revolves around calculating the x component of a position vector in a physics problem involving projectile motion and the influence of an electric field on a charged ball. Participants are examining the kinematic equations and the effects of forces acting on the ball.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate the time of flight and the x position using kinematic equations but is uncertain about the discrepancy between their result and the expected answer. Some participants question the assumption that the ball is not accelerating in the x-direction and suggest incorporating the force from the electric field into the calculations.

Discussion Status

Participants are actively exploring the implications of including the electric field's force and acceleration in the problem. There is a recognition of the need to adjust the kinematic equations to account for this additional acceleration, indicating a productive direction in the discussion.

Contextual Notes

There is a mention of the importance of including appropriate units when presenting numerical values, highlighting a constraint in the clarity of the original poster's calculations.

hraghav
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Homework Statement
A ball of mass 𝑚=4.07kg is thrown over level ground in a region where the electric field is 𝐸⃗=5.5N/C𝑖̂. The ball has a charge 𝑞=1.59C. The ball was thrown from the origin with an initial velocity of 𝑣⃗𝑖=5.58m/s𝑖̂+16.55m/s𝑘̂. Gravity provides an acceleration of 𝑔⃗=−9.8m/s^2𝑘̂. What is the x-component of the position vector where the ball lands?
Relevant Equations
t = 3.377s
x = 18.84m which is wrong
I first calculated the time using y = (viy)(t) + 0.5gt^2 where y is the vertical displacement which is 0 for the ball landing back on the ground, viy is the initial vertical velocity ie 16.55m/s and g = -9.8m/s}^2. I get 2 values for t, t=0 and t= 3.377s. Then using the equation x = (vix)(t) = (5.58m/s)(3.377s) I get x as 18.84m. The correct answer is 31.13m and I am not sure where I am going wrong.
Could someone please help me with this and let me know where am I making an error?
Thank you
 
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hraghav said:
Could someone please help me with this and let me know where am I making an error?
You are ignoring the force exerted by the electric field on the charged ball. What is that force? What acceleration does it provide? Rewrite the kinematic equations to reflect this correction.
 
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kuruman said:
You are ignoring the force exerted by the electric field on the charged ball. What is that force? What acceleration does it provide? Rewrite the kinematic equations to reflect this correction.
F = qE = 8.745 and acceleration = F/m = 2.148 but how do I use these values in my question?
 
hraghav said:
F = qE = 8.745 and acceleration = F/m = 2.148 but how do I use these values in my question?
You have assumed that the ball is not accelerating in the x-direction in your solution. This tells you that it does have a constant acceleration that you must incorporate. You have already handled one case of constant acceleration in this problem so doing it again should be relatively straightforward.

Note: Never ever write numbers without appropriate units.
 
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