Why has the model of the atom changed over time?
a.
the model of the atom evolved as scientists have made new discoveries.
b.
the model of the atom is only correct if it is identical to the size of an atom.
c.
the current model of the atom is simple with exaggerated size.
d.
atoms are too complex and cannot be explained using a model.

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?