Potential energy curve illustrating stable and unstable equilibrium points along a one-dimensional path.
Graph showing potential energy U(x) as a function of position x, with labeled points A through G indicating key features such as maxima, minima, and equilibrium positions.
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Step-by-step solution for: The figure below shows a graph of potential energy U x verses ...
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Show Answer Key & Explanations
Step-by-step solution for: The figure below shows a graph of potential energy U x verses ...
It looks like you've uploaded a graph of a potential energy function $ U(x) $ versus position $ x $. The task likely involves analyzing the motion of a particle in this potential, based on its total mechanical energy. Since I can't see the actual image, I will interpret the graph based on your description and common problems associated with such plots.
Let’s analyze the potential energy curve shown:
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- The vertical axis is $ U(x) $: potential energy.
- The horizontal axis is $ x $: position.
- Key points labeled: A, B, C, D, E, F, G.
- There's a dashed horizontal line passing through points A and G — this represents a constant total mechanical energy, say $ E $, for a particle moving in this potential.
We are to determine:
- The allowed regions of motion,
- The turning points,
- The stability of equilibrium points,
- Possible motion types (oscillatory, unbounded, etc.).
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#### 1. Total Energy Level
The dashed line at height $ U = E $ (through A and G) indicates the total mechanical energy of the particle. This is constant if no non-conservative forces act.
> Total energy: $ E = K + U $, where $ K \geq 0 $
So, the particle can only exist where $ U(x) \leq E $, because kinetic energy $ K = E - U(x) \geq 0 $.
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#### 2. Allowed Regions of Motion
We look for intervals where $ U(x) \leq E $:
- From the left: The potential starts high, decreases linearly to point A, then continues downward.
- At point A: $ U = E $
- Between A and B: $ U < E $ → allowed
- From B to C: $ U < E $ → allowed
- From C to D: $ U < E $ → allowed
- From D to E: $ U < E $ → allowed
- From E to F: $ U < E $ → allowed
- From F to G: $ U < E $ → allowed
- At G: $ U = E $
- Beyond G: $ U > E $ → not allowed (since $ K < 0 $)
So, the particle is confined between A and G, because beyond G, $ U > E $, which is not allowed.
> ✔ Allowed region: $ x \in [A, G] $
But wait — what about the left side?
- To the left of A: $ U > E $ → forbidden
- So, A is a turning point.
Similarly, at G, $ U = E $, so it's also a turning point.
Thus, the classical turning points are at A and G.
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#### 3. Equilibrium Points
Equilibrium occurs where $ \frac{dU}{dx} = 0 $, i.e., where the slope of the potential is zero.
Look at the labeled points:
- B: Slope changes from negative to positive → local minimum? Wait, let's check:
- From A to B: decreasing → slope negative
- From B to C: still decreasing → slope still negative
- So B is not a critical point.
Wait — we need to find where the slope is zero.
Looking at the shape:
- C: Minimum → $ \frac{dU}{dx} = 0 $ → stable equilibrium
- D: Local maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
- E: Minimum → $ \frac{dU}{dx} = 0 $ → stable equilibrium
- F: Local maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
- G: Maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
So equilibrium points: C, D, E, F, G
- Stable: C, E
- Unstable: D, F, G
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#### 4. Motion of the Particle
Given that the total energy $ E $ is equal to $ U $ at A and G, the particle will oscillate between these two points.
But note: between A and G, there are two valleys (minima at C and E), separated by barriers (maxima at D and F).
Let’s examine the possible motions:
- If the particle starts at A, it will move rightward into the potential well.
- It can go down to C, then up over D, but since $ U(D) < E $, it can pass over D.
- Then it goes to E, then up over F, but again $ U(F) < E $, so it can pass over F.
- Then it reaches G, where $ U = E $, so it turns around and comes back.
So, the particle can oscillate between A and G, passing through both wells.
But here's an important detail: Is the particle trapped in one well or can it move between them?
- The barrier at D: $ U(D) < E $ → yes, it can cross
- The barrier at F: $ U(F) < E $ → yes, it can cross
So, the particle can move freely between the two potential wells.
> ✔ The motion is oscillatory between A and G, with turning points at A and G.
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#### 5. What if Energy Were Lower?
If $ E $ were below the level of D or F, the particle would be trapped in one well.
But here, since $ E > U(D) $ and $ E > U(F) $, the particle can explore both wells.
---
Assuming the question is asking:
> "For a particle with total energy $ E $ as shown (dashed line), describe its motion."
Then the answer is:
---
- The particle has total energy $ E $, represented by the dashed line.
- It can only move in regions where $ U(x) \leq E $, which is between points A and G.
- Therefore, the turning points are at A and G.
- The particle will oscillate periodically between A and G.
- It passes over the local maxima at D and F (since $ U(D) < E $, $ U(F) < E $), so it can move between the two potential wells.
- The stable equilibrium points are at C and E.
- The unstable equilibrium points are at D, F, and G.
> 🔍 Conclusion: The particle undergoes bounded oscillatory motion between points A and G, traversing both potential wells.
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- If the energy were slightly lower than at G, but still above D and F, the motion would still be between A and G.
- If the energy were less than $ U(D) $, the particle would be trapped in either the left or right well depending on initial position.
- If the energy were greater than the highest peak (say, above G), the motion would be unbounded.
But in this case, since $ E = U(G) $, and $ U(G) $ is a local maximum, the particle just barely reaches G and turns around.
---
Let me know if you have a specific question (e.g., "Where is the particle most likely to be found?", "What happens if energy increases?", "Which points are stable?", etc.), and I can tailor the answer accordingly!
Let’s analyze the potential energy curve shown:
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Graph Description (based on your diagram):
- The vertical axis is $ U(x) $: potential energy.
- The horizontal axis is $ x $: position.
- Key points labeled: A, B, C, D, E, F, G.
- There's a dashed horizontal line passing through points A and G — this represents a constant total mechanical energy, say $ E $, for a particle moving in this potential.
We are to determine:
- The allowed regions of motion,
- The turning points,
- The stability of equilibrium points,
- Possible motion types (oscillatory, unbounded, etc.).
---
Step-by-step Analysis:
#### 1. Total Energy Level
The dashed line at height $ U = E $ (through A and G) indicates the total mechanical energy of the particle. This is constant if no non-conservative forces act.
> Total energy: $ E = K + U $, where $ K \geq 0 $
So, the particle can only exist where $ U(x) \leq E $, because kinetic energy $ K = E - U(x) \geq 0 $.
---
#### 2. Allowed Regions of Motion
We look for intervals where $ U(x) \leq E $:
- From the left: The potential starts high, decreases linearly to point A, then continues downward.
- At point A: $ U = E $
- Between A and B: $ U < E $ → allowed
- From B to C: $ U < E $ → allowed
- From C to D: $ U < E $ → allowed
- From D to E: $ U < E $ → allowed
- From E to F: $ U < E $ → allowed
- From F to G: $ U < E $ → allowed
- At G: $ U = E $
- Beyond G: $ U > E $ → not allowed (since $ K < 0 $)
So, the particle is confined between A and G, because beyond G, $ U > E $, which is not allowed.
> ✔ Allowed region: $ x \in [A, G] $
But wait — what about the left side?
- To the left of A: $ U > E $ → forbidden
- So, A is a turning point.
Similarly, at G, $ U = E $, so it's also a turning point.
Thus, the classical turning points are at A and G.
---
#### 3. Equilibrium Points
Equilibrium occurs where $ \frac{dU}{dx} = 0 $, i.e., where the slope of the potential is zero.
Look at the labeled points:
- B: Slope changes from negative to positive → local minimum? Wait, let's check:
- From A to B: decreasing → slope negative
- From B to C: still decreasing → slope still negative
- So B is not a critical point.
Wait — we need to find where the slope is zero.
Looking at the shape:
- C: Minimum → $ \frac{dU}{dx} = 0 $ → stable equilibrium
- D: Local maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
- E: Minimum → $ \frac{dU}{dx} = 0 $ → stable equilibrium
- F: Local maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
- G: Maximum → $ \frac{dU}{dx} = 0 $ → unstable equilibrium
So equilibrium points: C, D, E, F, G
- Stable: C, E
- Unstable: D, F, G
---
#### 4. Motion of the Particle
Given that the total energy $ E $ is equal to $ U $ at A and G, the particle will oscillate between these two points.
But note: between A and G, there are two valleys (minima at C and E), separated by barriers (maxima at D and F).
Let’s examine the possible motions:
- If the particle starts at A, it will move rightward into the potential well.
- It can go down to C, then up over D, but since $ U(D) < E $, it can pass over D.
- Then it goes to E, then up over F, but again $ U(F) < E $, so it can pass over F.
- Then it reaches G, where $ U = E $, so it turns around and comes back.
So, the particle can oscillate between A and G, passing through both wells.
But here's an important detail: Is the particle trapped in one well or can it move between them?
- The barrier at D: $ U(D) < E $ → yes, it can cross
- The barrier at F: $ U(F) < E $ → yes, it can cross
So, the particle can move freely between the two potential wells.
> ✔ The motion is oscillatory between A and G, with turning points at A and G.
---
#### 5. What if Energy Were Lower?
If $ E $ were below the level of D or F, the particle would be trapped in one well.
But here, since $ E > U(D) $ and $ E > U(F) $, the particle can explore both wells.
---
Answer Summary:
Assuming the question is asking:
> "For a particle with total energy $ E $ as shown (dashed line), describe its motion."
Then the answer is:
---
✔ Solution:
- The particle has total energy $ E $, represented by the dashed line.
- It can only move in regions where $ U(x) \leq E $, which is between points A and G.
- Therefore, the turning points are at A and G.
- The particle will oscillate periodically between A and G.
- It passes over the local maxima at D and F (since $ U(D) < E $, $ U(F) < E $), so it can move between the two potential wells.
- The stable equilibrium points are at C and E.
- The unstable equilibrium points are at D, F, and G.
> 🔍 Conclusion: The particle undergoes bounded oscillatory motion between points A and G, traversing both potential wells.
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📌 Additional Notes:
- If the energy were slightly lower than at G, but still above D and F, the motion would still be between A and G.
- If the energy were less than $ U(D) $, the particle would be trapped in either the left or right well depending on initial position.
- If the energy were greater than the highest peak (say, above G), the motion would be unbounded.
But in this case, since $ E = U(G) $, and $ U(G) $ is a local maximum, the particle just barely reaches G and turns around.
---
Let me know if you have a specific question (e.g., "Where is the particle most likely to be found?", "What happens if energy increases?", "Which points are stable?", etc.), and I can tailor the answer accordingly!
Parent Tip: Review the logic above to help your child master the concept of potential energy diagrams worksheet answer key chapter 12.