You want to use a rope to pull a 12-kg box of books up a plane inclined 30∘ above the horizontal. The coefficient of kinetic friction is 0.27. The rope pulls parallel to the incline. What force do you need to exert on the rope if you want to pull the box at constant speed.

Which of the statements about waves is true? a. in longitudinal waves, particles move perpendicular to the direction the wave is traveling. b. both transverse and longitudinal waves can travel through water c. electromagnetic waves are a type of longitudinal waves. d. in a transverse wave, particles move parallel to the direction the wave is traveling.

Aboxcar traveling at 12 m/s approaches a string of 5 identical boxcars sitting stationary on the track. the moving boxcar collides and links with the stationary cars and they all move off together along the track. what is the final speed of the cars immediately after the collision? (you may take the mass of each boxcar to be 18,537 kg.)

Ms. hidalgo opens the door to her classroom. her classroom is 60 degrees and the air outside is 80. predict what will happen using your knowledge of how heat flows.