Answer:
b
Explanation:
n = m(g +a)
n= normal force (N)
m=mass (kg)
g=acceleration of gravity
a= acceleration of elevator
rearrange:
a= n/m - g
a= (810 N/73 kg) - 9.8 m/s ^2
a= 1.3 m/s ^2 up
and the acceleration is upwards bc her weight is less than the scale reading
B. Frequency remains unchanged because the energy in a photon is E=hf. So if the frequency changes so does the energy and that doesn't happen to EM waves entering a medium by the conservation of energy
