What happens when two objects with different masses collide?

if the colliding objects have unequal mass, they will have unequal accelerations as a result of the contact force that results during the collision.

The object with the bigger mass will most likely push the smaller one back or if their big enough the big one will obliterate the small one (take a smart car going head on with a semi for example). unless it's something like a weather balloon vs. a car, then the balloon would have the bigger mass and the car would be smaller mass, but it would still push back the weather balloon.

explanation:

metals have excess of electrons whereas non-metals have deficiency of electrons. thus, in order to gain stability metals easily donate their electrons to the non-metals.

for example, electronic configuration of sodium is and electronic configuration of phosphorous is .

when a phosphorous atom and sodium atom combine together then sodium will donate is extra one electron to the phosphorous atom. as a result there will be formation of ionic bond between sodium and phosphorous.

the reaction will be as follows.

there, are three sodium sodium atoms and each of them will donate its one extra electron to phosphorous atom. thus, the sub-shell of phosphorous gets completely filled.  

thus, we can conclude that electrons are transferred from atoms of sodium to atoms of phosphorous. this transfer makes the sodium atoms donate one electron and the phosphorous atoms to gain one electron. as a result, the sodium and phosphorus atoms strongly attract each other.