as101 lesson 5

Isaac Newton contribution

Developed three laws of motion and universal law of gravity

Newton First Law

Object stays at rest or constant velocity unless net force acts

Newton Second Law

Greater force causes greater acceleration

Newton Third Law

For every action force there is equal and opposite reaction force

Universal gravitation

All masses attract each other

Gravity depends on mass

More mass means stronger gravitational force

Gravity depends on distance

Greater distance means weaker force (inverse square)

Why Moon orbits Earth

Earth’s gravity pulls Moon inward

Stable orbit

Object constantly falls toward planet but keeps missing it

Closed orbit

Bound orbit that repeats

Open orbit

Unbound orbit that escapes

Speed

Distance traveled divided by time

Velocity

Speed with direction

Velocity changes if

Speed changes or direction changes

Acceleration

Rate of change of velocity

Acceleration examples

Speeding up, slowing down, turning

Acceleration due to gravity on Earth

9.8 m/s² downward

Momentum

Mass × velocity

Conservation of momentum

Total momentum stays constant unless external force acts

Mass

Amount of matter in object

Weight

Force of gravity acting on object

Mass vs weight

Mass constant; weight changes with gravity

ISS astronauts not truly weightless

They are in continuous free fall orbit around Earth

Heat

Transfer of thermal energy from hotter object to cooler object

Temperature

Measure of average kinetic energy of particles

Three heat transfer methods

Conduction, convection, radiation

Conduction

Heat transfer through direct contact/particle collisions

Convection

Heat transfer by movement of fluid (liquid or gas)

Radiation

Heat transfer by electromagnetic waves; no medium needed

Fahrenheit scale

Water freezes 32°, boils 212°

Celsius scale

Water freezes 0°, boils 100°

Kelvin scale

Absolute temperature scale used in science

0 K

Absolute zero lowest possible temperature

Kelvin vs Celsius

Same size increments, Kelvin shifted upward by 273.15

Hotter objects radiate

More total energy and shorter wavelength ligh