A 2.5 kg stone is released from rest and falls toward Earth. After 4.0 s, magnitude of its momentum in kg. m/s is :
A-78
B-98
C-122.5
D-24.7

What are some properties of transverse waves?

Does heating a metal wire increase or decrease its electrical resistance? why?

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