Amass of 9 kilograms is lifted through a height of 17 meters. how much work is done during the lifting?

(how do we get to the answer as well)

Matter that emits no light at any wavelength is called

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

What kind of waves require a medium to travel? question 6 options: light waves mechanical waves all waves need a medium to travel electromagnetic waves