Suppose there was a star with a parallax angle of 1 arcsecond. How far away would it be?

Standing side by side ,you and a friend step off a bridge at different times and fall for 1.6s to the water below.your friend goes first,and you follow after he has dropped a distance of 2.0m.when your friend hits the water,is the seperation between the two of you 2.0m or more than 2.0m? verify your answer with a calculation.

What are similarities and differences between refraction, reflection, diffraction and absorption?

How to tell if two objects are in thermal equilibrium 1.the objects have the same temperature 2.the objects are the same size 3.the objects are touching each other 4.the objects temperatures are changing