Kinetic and Potential Energy in Simple Harmonic Motion

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Homework Help Overview

The discussion revolves around a problem involving kinetic and potential energy in the context of simple harmonic motion. The original poster is confused about various aspects of the problem, including the potential energy of an object at a specific displacement and the relationship between kinetic and potential energy.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate potential energy at a displacement of +4 cm but questions the validity of their approach after obtaining an answer exceeding total energy. They also express uncertainty about determining maximum displacement and solving for velocity without time or acceleration. Participants raise questions about unit consistency and the interpretation of displacement in the context of the problem.

Discussion Status

Participants are actively engaging with the problem, offering guidance on unit considerations and the relationship between potential and kinetic energy. There is a focus on clarifying the definitions and assumptions related to the displacement and energy calculations, but no consensus has been reached on the specific calculations or interpretations.

Contextual Notes

The problem includes specific constraints such as the total energy of the system and the requirement to consider the potential energy function. There is mention of a graph that is referenced but not provided, which may limit the discussion.

Tabe
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Kinetic and Potential Energy?

This problem is totally confusing me..can someone please explain it...:confused:

A 3.0 kg object subject to a restoring force F is undergoing simple harmonic motion with a small amplitude. The potential energy U of the object as a function of distance x from its equilibrium is shown. This particular object has a total energy E: of 0.4 J.

(a) What is the object's potential energy when its displacement is +4 cm from its equilibrium position?
For this problem, I used 4 cm as my displacement, but when I used it in the formula, I ended up getting an answer that is greater than the total energy, so I know it must be wrong. Am I using the wrong displacement?

(b) What is the farthest the object moves along the x-axis in the positive direction? Explain.
I really don't understand how to solve for the distand in the x-axis without having the acceleration or time. Is there a formula that I've overlooked or am I just making this problem more complicated than it is?

(c) Determine the object's kinetic energy when its displacement is -7 cm.
For this part, the kinetic energy equation is KE= 1/2mv^2. How do I solve for the velocity without time or acceleration?

(d) What is the object's speed at x= 0?
Again, I would need the answers from (c) to solve for the speed.
 
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Is there an image?
The potential energy U of the object as a function of distance x from its equilibrium is shown
 
For part 9 (a). Mind your units. The units for Joules is: 1 Joule = 1 kgm^2/s^2.
If you are using cm, you will not be getting Joules, but rather "centi-Joules" :P

For part (b). The energy of a oscillator can be expressed as the sum of it's potential (1/2kx^2) and kinetic (1/2mv^2). At max displacement, it has zero kinetic energy.
 
There is a graph of the distance and potential energy. When the problem states that it is 4cm from its equilibrium position, is it referring to the x or y component?
 
Tabe said:
When the problem states that it is 4cm from its equilibrium position, is it referring to the x or y component?

I believe we are talking about a 1 dimensional oscillator, and that dimension is the x?
 

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