Practice Flashcards
Flip to reveal answersDefine elastic potential energy.
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 14 Flashcards — Elastic potential energy
Sign up free to track progress and get spaced-repetition review schedules.
Question
Define elastic potential energy.
Answer
The energy **stored in a spring** (or springy material) when it is **stretched or squashed**. Unit: the joule (J).
Question
Formula for elastic potential energy?
Answer
$E_H = \tfrac{1}{2}k\,\Delta x^{2}$ — half × spring constant × extension squared. (Also written E_p = ½kx².)
Question
What is the spring constant k?
Answer
How **stiff** a spring is — the force needed per metre of stretch. Unit: N m⁻¹ (newtons per metre).
Question
What does Δx mean in E_H = ½kΔx²?
Answer
The **extension or compression** — how far the spring is stretched or squashed from its natural length, in metres.
Question
You double a spring's extension — what happens to the stored energy?
Answer
It becomes **four times** as big, because the extension is squared (2² = 4).
Question
How do you find the energy stored in a spring-coupled collision?
Answer
By conservation of energy: **E_H = kinetic energy before − kinetic energy of the combined motion**.
Question
How do you find the carts' common speed in a spring collision?
Answer
From **conservation of momentum**: total momentum before = (combined mass) × common speed.
Question
What is the unit of elastic potential energy?
Answer
The **joule (J)** — the same unit as all other forms of energy.
Question
Find the energy stored: k = 300 N m⁻¹, Δx = 0.020 m.
Answer
E_H = ½ × 300 × 0.020² = ½ × 300 × 0.0004 = 0.060 J.
Question
A spring releases 0.60 J in 0.015 s. Find the average power.
Answer
Power = energy ÷ time = 0.60 ÷ 0.015 = 40 W.
Question
Elastic PE vs gravitational PE — what's the difference?
Answer
Elastic PE (½kΔx²) is stored by **stretching/squashing** a spring; gravitational PE (mgΔh) is stored by **lifting** a mass to a height. Both are in joules.
Question
State Hooke's law.
Answer
The force on a spring is **proportional to its extension** (F = kΔx), up to the limit of proportionality.
Question
A ball on an elastic rope (length L) drops from the fixed end and stops at extension x. What energy equation holds at the lowest point?
Answer
**mg(L + x) = ½kx²**: all the PE lost is stored as elastic energy.
Question
What does the area under a force–extension graph give?
Answer
The **energy stored** (work done stretching): ½FΔx for a straight line through the origin.
Read the notes
Full study notes for Elastic potential energy
Topic 1.3 hub
Work, energy and power
More from Topic 1.3
All flashcards in this topic
Physics exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free