Respuesta :

Some objects are heavier then others because they have more mass. Exp: A bowling ball has more mass then that of a feather. A person has more mass then that of a bowling ball. And so on… 

Here's a quote to help! 

"Galileo discovered that objects that are more dense, or have more mass, fall at a faster rate than less dense objects, due to this air resistance. A feather and brick dropped together. Air resistance causes the feather to fall more slowly." 
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Universidad de Mexico