a 10kg box car rolls at 6m/s and crashes into a 20kg box car that is at rest. After the crash, both cars are stuck together. what is their velocity?​

Will you chech and finish these for me, because i am stumped with them.

This is a form of winter precipitation. it is frozen precipitation falling as ice pellets. snowflakes melt into raindrops as they pass through a thin layer of warmer air. the raindrops then refreeze into particles of ice when they fall into a layer of sub-freezing air near the surface of the earth. this precipitation is called a) hail. b) rain. c) sleet. d) snow.

Consider an air-filled charged capacitor. how can its capacitance be increased?