🪐 GCSE Physics Newsletter: Forces and Elasticity

Part 1 - Keywords:

• Force

• Elasticity

• Compression

• Tension

• Bending

• Deformation

• Elastic Deformation

• Inelastic Deformation

• Limit of Proportionality

• Hooke’s Law

Part 2 - Key Facts:

• Forces can stretch, bend, or compress objects.

• At least two forces must act on a stationary object to change its shape.

• Elastic deformation occurs when an object returns to its original shape after forces are removed.

• Inelastic deformation occurs when an object is permanently deformed and does not return to its original shape.

• Hooke’s Law: The extension of an elastic object (e.g., a spring) is directly proportional to the force applied, up to the limit of proportionality.

• If too much force is applied, the material is stretched beyond its limit, and it will not return to its original shape.

Part 3 - Quick Quiz:

1️⃣ What three ways can a force change an object’s shape?
2️⃣ Why must more than one force act on an object to change its shape?
3️⃣ What is the difference between elastic and inelastic deformation?
4️⃣ What happens when a spring is stretched beyond its limit of proportionality?
5️⃣ What is Hooke’s Law?

Part 4 - Answers:

1️⃣ A force can stretch, bend, or compress an object.
2️⃣ A stationary object needs at least two forces acting in opposite directions to change shape (otherwise, it would just move).
3️⃣ Elastic deformation is when an object returns to its original shape, while inelastic deformation is when it is permanently changed.
4️⃣ If stretched too far, the spring loses its elasticity and will not return to its original shape.
5️⃣ Hooke’s Law states that the extension of an elastic object is directly proportional to the force applied, up to the limit of proportionality.

Part 5 - Multiple Choice Questions:

1️⃣ What must happen for an object to be compressed, bent, or stretched?
a) A single force must act on it.
b) No force is required.
c) At least two forces must act on it.
d) The object must be in motion.

2️⃣ What happens if an elastic object is stretched beyond its limit of proportionality?
a) It extends proportionally to the force applied.
b) It returns to its original shape.
c) It no longer obeys Hooke’s Law and stays permanently deformed.
d) It becomes stronger.

3️⃣ A spring is stretched with increasing force. Up to a point, the extension increases proportionally. This means:
a) The spring follows Hooke’s Law.
b) The spring has exceeded the limit of proportionality.
c) The spring is undergoing inelastic deformation.
d) No work is done on the spring.

Part 6 - Multiple Choice Answers:

1️⃣ c) At least two forces must act on it.
2️⃣ c) It no longer obeys Hooke’s Law and stays permanently deformed.
3️⃣ a) The spring follows Hooke’s Law.

Part 7 - Going Further:

Question:
Why does a rubber band not obey Hooke’s Law, while a metal spring does?

Answer:
A rubber band does not stretch in a way that is directly proportional to the applied force. Instead, it follows a non-linear relationship, meaning small increases in force can cause large or unpredictable extensions. In contrast, a metal spring follows Hooke’s Law, where force and extension are proportional until the limit of proportionality is reached.

Part 8 - Revision Tip:

✔️ Remember: Hooke’s Law only applies up to the limit of proportionality!
✔️ Practice: Try stretching different materials (e.g., rubber bands, plastic rulers, and springs) and observe which ones return to their original shape.

💡 Fun fact: NASA engineers use Hooke’s Law to design spacecraft materials that can handle stretching and compressing forces in space! 🚀

Part 9 - More Help:

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Stay tuned for the next issue, where we'll explore another key physics concept! ⚡🔬

Until next time keep revising!