1. A 40 kg rock falls from rest from the top of a 64 m high tower and falls with negligible air resistance. How much kinetic energy (KE) and potential energy (PE) does the rock have when it is 28 m above the ground?
(A) KE = 0; PE = 2.5 x 104

J (B) KE = 1.1 x 104 J; PE = 1.4 x 104

J (C) KE = 1.4 x 104 J; PE = 1.1 x 104

J (D) KE = 2.5 x 104 J; PE = 0

Imagine you are riding on a yacht in the ocean and traveling at 20 mph. you then hit a golf ball at 100 mph from the deck of the yacht. you see the ball move away from you at 100mph, while a person standing on a near by beach would observe your golf ball traveling at 120 mph (20 mph + 100 mph). now imagine you are aboard the hermes spacecraft traveling at 0.1c (1/10 the speed of light) past mars and shine a laser from the front of the ship. you would see the light traveling at c (the speed of light) away from your ship. according to einstein’s special relativity, how fast will a person on mars observe the light to be traveling? a) 0.1c (1/10 the speed of light) b) c (the speed of light) c)1.1c (c+0.1c)

The seven sisters, seven stars located more than 400 light-years away in the taurus constellation can be seen here with venus and another constellation, orion. the seven stars stay grouped together but seem to move, like the planet venus. why do stars seem to move like planets in the night sky?

Find the magnetic field a distance r from the center of a long wire that has radius a and carries a uniform current per unit area j in the positive z direction.