Answer all the questions will mark as brainliest 20 points

Ineed extreme for task 2. my student number is 571721. many to whoever solves this correctly, im in debt to you.

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 was the first instrument to ever record an earthquake?