Newton's Laws
Physics · न्यूटन के नियम · 20 facts
Newton's 1st Law (Inertia): object at rest stays at rest, moving stays moving unless external force acts
Inertia: tendency of body to resist change in state of motion or rest
Example 1st Law: passengers jerk forward when bus stops suddenly
Mass is measure of inertia; heavier objects have more inertia
Newton's 2nd Law: Force = mass x acceleration (F=ma); unit = Newton (N)
2nd Law: rate of change of momentum equals applied force
Momentum (p) = mass x velocity; unit = kg.m/s; vector quantity
Newton's 3rd Law: every action has an equal and opposite reaction
3rd Law examples: rocket propulsion, gun recoil, swimming (push water back)
Action and reaction act on DIFFERENT bodies; they do NOT cancel each other
Law of Conservation of Momentum: total momentum before = after collision (no external force)
Impulse = Force x Time = Change in momentum; catching ball with more time reduces force
Balanced forces: net force=0, no acceleration; Unbalanced: net force nonzero, causes acceleration
1 Newton = force to accelerate 1 kg mass by 1 m/s2
Elastic collision: kinetic energy conserved; Inelastic: kinetic energy NOT conserved
Cricket fielder pulls hands back while catching to increase time and reduce impact force
Newton published laws in Principia Mathematica (1687)
Walking: foot pushes ground backward (action), ground pushes foot forward (reaction)
Weightlessness in orbit: astronauts in continuous free fall around Earth
Friction is NOT part of Newton's Laws but affects all real-world motion