Why does the doppler method generally allow us to determine only minimum planetary masses?

How would doubling the made of an object change the objects potential energy

A2 kg ball travellng to the right with a speed of 4 m/s collidees with a 5 kg ball traveling to the left with a speed of 3 m/s. take right to be the positive direction. what is the total momentum of the two balls before they collide? what is the total momentum of the two balls after they collide?

Which type of bond is found between the atoms of a molecule? a. metallic b. delocalized electron c. covalent d. ionic