Why should we use the metric system in science?

In what direction does the medium move relative to the direction of the wave? explain.

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.)

What should the power status of a circuit be when measuring resistance with an ohmmeter?