Find earth's approximate mass from the fact that the moon orbits earth in an average time of 27.3 days at an average distance of 384,000 kilometers. (hint: the moon's mass is only about 180 of earth's.)

Sort the images based on whether there's a force of attraction or repulsion between the magnets shown. attraction repulsion

Acamcorder has a power rating of 20 watts. if the output voltage from its battery is 9 volts, what current does it use?

In an old-fashioned amusement park ride, passengers stand inside a 3.0-m-tall, 5.0-m-diameter hollow steel cylinder with their backs against the wall. the cylinder begins to rotate about a vertical axis. then the floor on which the passengers are standing suddenly drops away! if all goes well, the passengers will “stick” to the wall and not slide. clothing has a static coefficient of friction against steel in the range 0.60 to 1.0 and a kinetic coefficient in the range 0.40 to 0.70. part a what is the minimum rotational frequency, in rpm, for which the ride is safe? express your answer using two significant figures. f f = rpm