A 20 kg dog runs at + 2.5 m/s and collides with a 10 kg piece of on a frozen lake. After the collision we know that the 20 kg dog was moving - 2 m/s BACKWARDS, and the ice was moving the same way as the dog at - 5.0 m/s How fast AND in which direction was the piece of ice moving BEFORE the collision?

Aprotein molecule in an electrophoresis gel has a negative charge. the exact charge depends on the ph of the solution, but 30 excess electrons is typical. what is the magnitude of the electric force on a protein with this charge in a 1600n/c electric field? write in two significant numbers, and also in newton