Question 1

What does the slope of a potential energy curve tell you about the force acting on a system?

Accepted Answer

The force acting on a system equals the negative slope of the potential energy curve. At points where the slope is zero, such as at local minima or maxima, the net force is zero. Where the slope is positive, a restoring force acts on the system, while a negative slope indicates a force directed away from equilibrium.

Question 2

How do you distinguish between stable and unstable equilibrium points on an energy diagram?

Accepted Answer

Stable equilibrium occurs at local minima where any displacement produces a restoring force directed back toward the equilibrium point. Unstable equilibrium occurs at local maxima where any displacement produces a force directed away from the point. The slope behavior at these locations determines system stability.

Question 3

What happens to a skater on a parabolic ramp when total energy equals E1 versus E2?

Accepted Answer

When total energy is E1, the skater remains trapped between two positions on the ramp, unable to escape beyond the boundaries. When total energy is E2, the skater possesses sufficient energy to escape and move beyond the higher potential energy barrier, allowing the system to reach regions previously inaccessible.

Question 4

What characterizes a neutral equilibrium point on a potential energy diagram?

Accepted Answer

A neutral equilibrium point occurs where potential energy remains constant across a region, resulting in zero net force. Movement in either direction from this position produces no restoring or disrupting force, distinguishing it from stable minima and unstable maxima where forces actively respond to displacement.

Question 5

Why is understanding energy diagram topology important for analyzing system dynamics?

Accepted Answer

Energy diagram topology reveals equilibrium points and system stability, allowing prediction of motion and energy constraints. The shape of the potential energy curve determines whether a system remains confined or can escape, and whether forces will restore or disrupt equilibrium, essential for understanding physical behavior.

Question 6

How does the concept of local minima relate to system behavior in energy diagrams?

Accepted Answer

Local minima represent stable equilibrium points where potential energy is lowest and the system naturally tends to remain indefinitely without external forces. The zero slope at minima indicates zero net force, while positive slopes on either side ensure restoring forces push the system back toward this stable position.

Question 7

What role does total mechanical energy play in determining whether a system can escape a potential well?

Accepted Answer

Total mechanical energy determines the accessible region of motion on an energy diagram. If total energy exceeds the potential energy barrier at a local maximum, the system can escape beyond that point. If total energy is lower, the system remains confined between boundaries defined by where total energy equals potential energy.

エネルギー図 - II