This essay focuses on the direction of gravitational force.. Watch the following video by Terence Tao on Cosmic Distance Ladder and write a 200-word

the direction of gravitational force

PHY100 2021 Homework 3 Due by May 25, 2021, 5 pm Weight 8% 1. Watch the following video by Terence Tao on Cosmic Distance Ladder and write a 200-word report on your favorite part of the talk. The talk is available at: https://www.youtube.com/watch?v=7ne0GArfeMs. His slides for the talk are available here: https://terrytao.files.wordpress.com/2010/10/cosmic-distance-ladder2.pptx (20 pts) 2. Principle of inertia and gravity. Consider a boat coasting on a quiet lake with a ball hung at the top of its mast. At a certain time ball is let go. Plot the trajectory of the ball and the boat as seen by: a.

A person on the boat (5 pts) b. A person on ground

(10 pts) c. Do both people see the ball hitting the same spot on the boat or different? (5 pts) Explain your trajectories for the two cases. 3. Earth and moon: a. What is the direction of gravitational force between earth and moon? (5 pts) b. Is the Moon falling towards the earth? Explain your answer. (5 pts) c. What would be the trajectory of earth’s moon if suddenly earth’s gravitation field vanished? (5 pts) 4. Kepler’s laws: a. Kepler observedplanets  that sweep out equal area in equal time, but the speed at which planets move at different parts of the orbit is not constant. Why is it so? Explain your answer. (10 pts) b. Does Earth travel fastest when

it’s closest to the Sun or when it’s the farthest?

Explain using Kepler’s laws. (5 pts) c. What kind (shape) of an orbit will allow Kepler’s area law to hold but now the planets can have constant speed throughout its orbit. Justify your choice of shape? (10 pts) 5. Summarize your understanding of what one means by “universality of a law” using Newton’s law of gravitation as an example, in no more than 100 words. If you use any resource to answer this please cite it. (10 p