IB Physics Theme D essentials

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Keppler’s first law

Planets orbit the sun in a n ellipse with the sun at the focus

Keppler’s second law

Planets move faster closer to the sun. A line joining a planet to the sun sweeps out equal areas in the same time.

Keppler’s third law

For a circle, R³ is proportional to T². For an ellipse, R is the semi major maxis.

Gravitational potential

Work don per unit mass in bringing a mass from infinitiy to a point.

Kinetic energy

-GMm/2r = -E_P/2

Total energy

-GMm/2r = -E_K

What happens to height and velocity when there is viscous drag?

Height decreases, velocity increases

Why oil drops?

They don’t evaporate

electric potential

work done per unit charge to move a small test charge from a point of zero potential to a specific point