Back to the full dot-point answer
WalesPhysicsQuick questions
Unit 4 Fields and their Applications
Quick questions on Orbits and the wider universe: Kepler's third law and dark matter - WJEC A-Level Physics
5short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is circular orbits under gravity?Show answer
Notice the orbiting body's own mass cancels: the orbital speed depends only on the central mass and the radius , not on how heavy the satellite is.
What is kepler's third law?Show answer
Combining the orbital condition with gives Kepler's third law: the square of the orbital period is proportional to the cube of the orbital radius.
What are satellites?Show answer
A geostationary satellite orbits once every 24 hours above the equator, so it stays above a fixed point on Earth, useful for communications. Low polar orbits suit imaging and monitoring because they pass over different strips of the planet on each pass.
What is q1?Show answer
Show that the orbital speed of a satellite is . [2 marks]
What is q2?Show answer
State the evidence from galactic rotation curves for dark matter. [2 marks]
Have a question we have not covered?
This dot-point answer is short enough that we have not extracted many short questions yet. Read the full dot-point answer or ask Mo, our study assistant, in the chat for follow ups.