I believe the answer is A
Answer:
The mass of the massive object at the center of the Milky Way galaxy is 
Explanation:
Given that,
Diameter = 10 light year
Orbital speed = 180 km/s
Suppose determine the mass of the massive object at the center of the Milky Way galaxy.
Take the distance of one light year to be 9.461×10¹⁵ m. I was able to get this it is 4.26×10³⁷ kg.
We need to calculate the radius of the orbit
Using formula of radius



We need to calculate the mass of the massive object at the center of the Milky Way galaxy
Using formula of mass

Put the value into the formula


Hence, The mass of the massive object at the center of the Milky Way galaxy is 
Answer:
The period of motion of new mass T = 0.637 sec
Explanation:
Given data
Mass of object (m) = 9 gm = 0.009 kg
Δx = 3.5 cm = 0.035 m
We know that spring force is given by
F = m g
F = 0.009 × 9.81 = 0.08829 N
Spring constant


k = 2.522 
New mass
= 26 gm = 0.026 kg
Now the period of motion is given by


T = 0.637 sec
This is the period of motion of new mass.