A 25 metric ton train moves toward the south at 70 m/s. At what speed must it travel to have three times its original momentum (to 2 sig figs)?

Which feature indicates that mars resides in the inner region of the solar system

Yvette hangs a 2.4kg bird feeder in the middle of a rope tied between two trees. the feeder creates a tension of 480 n in each side of the the rope.

Consider an insulating crystal, made up of layers of atoms. what form would you expect the temperature dependence of the phonon heat capacity to approach at extremely low temperatures if the interlayer coupling is i)very strong (rigid coupling), and ii) very weak. explain.