Physics – Last‑Minute Points to Remember

1. Describing Motion  

When answering motion questions, always:  

- State the force acting on the object.  

- Mention the direction of acceleration.  

- Describe how acceleration changes (constant, increasing, or decreasing).  

- Add details about momentum if relevant.  

2. Binding Energy Graph  

- The graph of binding energy per nucleon (y‑axis) against nucleon number (x‑axis) peaks at A ≈ 56 (iron).  

3. Expanding Universe – Emission Spectra  

- Observed wavelengths from galaxies are greater than actual wavelengths.  

- This redshift indicates that galaxies are moving away from Earth.  

- Conclusion: The universe is expanding.  

4. Hubble’s Law and the Big Bang Theory  

- Hubble’s Law: More distant galaxies move away faster.  

- Observations show that all parts of the universe are receding from each other.  

- This implies that matter must have been close together in the past.  

- Leads to the conclusion: the universe began with a Big Bang.