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Free fall velocity
If an apple falls from a tree and hits the ground in 2 sec, how fast is it moving just before impact?
How is atomic number different from mass number?
Students often mix these up—what’s the difference?
Average velocity
A runner covers 100 m east, then 100 m west in 20 sec total. What’s their average velocity?
Why do different elements emit different colors in flame tes...
Sodium glows yellow, copper gives green — why?
Non-zero acceleration
Can a body have zero velocity but non-zero acceleration?
What are energy shells or orbitals?
Why do electrons “orbit” at fixed distances?
Instantaneous speed
What’s the speed of a car at the exact moment a speedometer reads 80 km/h?
What’s the difference between an ion and an atom?
Why does sodium become Na⁺ in compounds?
Uniform circular motion
Why is a satellite in circular orbit said to accelerate even at constant speed?
Why is Rutherford’s gold foil experiment famous?
What did firing alpha particles at gold tell us?
Inertia
Why do we fall backward when a bus suddenly starts moving?
What is the significance of Bohr’s atomic model?
Why is it still taught?
Mass vs weight
Is your weight the same on Earth and the Moon?
Why are electrons not pulled into the nucleus?
If opposite charges attract, why don’t electrons crash into protons?
Balanced vs unbalanced forces
If you push a table with 20 N and a friend pushes opposite with 20 N, does the table move?
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