A child watches an animation in a planetarium. Fig. 1 shows the orbit of a fictional planet around its star. At P the planet is closest to the star, and at ...
Question 1 Report
A child watches an animation in a planetarium. Fig. 1 shows the orbit of a fictional planet around its star. At P the planet is closest to the star, and at Q it is furthest away. The animation uses a line of light to show one complete path. The presenter says that the planet's velocity is not constant throughout the orbit, even though it returns to the same point each year.
(a) What is the name of the path followed by the planet? [1]
(b) Describe the difference between the planet's speed at P and at Q. [1]
(c) Explain why the planet changes direction as it moves around the star. [2]
Answer Details
(a) The path followed by the planet is an orbit. [1]
(b) The planet is faster at P, where it is closest to the star, than at Q. [1]
(c) The star gravitationally attracts the planet. This force acts towards the star and changes the direction of the planet's motion, producing its curved orbital path. [2]
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