Question about forces and acceleration

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Homework Help Overview

The discussion revolves around a physics problem involving forces and acceleration acting on a lemon half on a frictionless table. The problem specifies two horizontal forces with given magnitudes and angles, as well as the mass of the lemon half and its velocity as a function of time.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to derive acceleration from velocity and apply Newton's second law to find the forces. Some participants question the correctness of the acceleration calculation and suggest that a typo may have occurred in the original poster's expression for acceleration.

Discussion Status

Participants are engaged in clarifying the original poster's calculations and understanding the problem setup. There is an acknowledgment of potential errors in the original poster's work, and requests for additional information, such as a diagram and detailed calculations, have been made to facilitate further discussion.

Contextual Notes

The discussion highlights the need for visual aids to better understand the forces involved, as well as the importance of accurate notation in mathematical expressions. The original poster's calculations and assumptions are under scrutiny, indicating a collaborative effort to clarify the problem.

kevinf
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Homework Statement


Figure 5-40 shows an overhead view of a lemon half and two of the three horizontal forces that act on it as it is on a frictionless table. Force F1 has a magnitude of 4.40 N and is at theta1 = 30°. Force F2 has a magnitude of 7.00 N and is at theta2 = 30°. The lemon half has mass 0.0300 kg.

(c) varying velocity v = (13.0t i - 14.0t j) m/s, where t is time in seconds

Homework Equations



F = MA

The Attempt at a Solution



i took the derivative of the velocity to get the acceleration which would be (13.0i + 14.0j)m/(s^2). i then multiply the components of the accleeration with the mass to get the forces of the acclereation. then i added the x component of force 1 and force 2 and a variable x and set it equal to the x component of the acceleration force. am i doing this right because i am not gettign the right answer
 
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Sounds like you have the right idea. But it is difficult to check your work without a picture... one thing... it's probably just a typo. you wrote acceleration is (13.0i + 14.0j)m/(s^2), but the derivative of:

v = (13.0t i - 14.0t j) m/s

is 13.0i - 14.0j not plus...
 
yeah that's what i meant
 
kevinf said:
yeah that's what i meant

can you describe the picture and the 3 forces... or better yet post a picture?

Also can you show your calculations?
 

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