What happens to the total mass of a substance undergoing a physical change?
only have eight

The total mass has to stay constant in any process, change, or
procedure, even if some of it gets away from you. 

Mass never just appears out of nothing, and it never just disappears. 
If it seems like the mass changed, then the extra mass had to come
from somewhere, or the missing mass had to go somewhere.
The total amount never changes.

Answer: it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.explanation:   we have equation of motion ,where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.average velocity = displacement/ time taken.average velocity = 10.69 miles/hr = 10.69*1.6*1000/(60*60) = 4.75 m/s4.75 = s/ts = 4. 1we also have acceleration = 2.18 m/s², initial velocity = 0 m/sso it will take   4.36 seconds to reach her average velocity 10.69 miles/hour.

Ithink it is letter b, i may be wrong but i think that is the answer