psic nweton

Newton’s First Law

(Inertia) Objects resist changes in motion unless acted on by a net external force.

Inertia

The tendency of an object to resist changes in its motion.

Mass (physics)

A measure of inertia; the amount of matter in an object, measured in kilograms.

Newton’s Second Law

F(net) = m × a; acceleration depends on net force and mass.

Net Force

The overall force acting on an object after all forces are combined.

Newton’s Third Law

For every action force, there is an equal and opposite reaction force.

Galileo’s Law of Falling

Without air resistance, all objects fall at the same rate.

Weight

The force of gravity acting on an object.

Weight Formula

Fg = m × g

Gravity (g)

The acceleration due to gravity; about 9.8 m/s² on Earth.

Mass vs Weight

Mass stays the same everywhere; weight depends on gravity.

Free Fall

Motion under the influence of gravity only.

Universal Law of Gravitation

Fg = (G × m1 × m2) / r²

Effect of Distance on Gravity

Doubling distance makes gravity 1/4 as strong; halving distance makes it 4 times stronger.

Gravitational Field Strength Formula

g is proportional to M / r²

Planet Gravity Rule

Larger mass increases gravity; larger radius decreases gravity.

Static Friction.

Friction that prevents motion from starting

Kinetic Friction

Friction that opposes motion once an object is moving.

Static vs Kinetic Friction

Static friction is greater than kinetic friction.

Apparent Weight

The normal force measured by a scale.

Normal Force

The support force exerted by a surface.

Elevator Accelerating Up

FN = mg + ma (scale reads heavier)

Elevator Accelerating Down

FN = mg − ma (scale reads lighter)

Elevator at Constant Velocity

FN = mg (scale reads true weight)

Inertia in Car Crashes

Loose objects keep moving forward when a car stops suddenly.