Two spaceships are approaching each other. (a) if the speed of each is 0.9c relative to earth, what is the speed of one relative to the other? (b) if the speed of each relative to earth is 30,000 m/s (about 100 times the speed of sound), what is the speed of one relative to the other?

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

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

A0.750 kg aluminum pan is removed from the stove and plunged into a sink filled with 10.0 kg of water at 293 k. the water temperature quickly rises to 297 k. what was the initial temperature of the aluminum pan? the specific heat of aluminum is ca = 900 j/(kgk) and water is cw = 4190 j/(kgk)