Wow ! They could set up sheets of "slow glass" beside beautiful forests with rivers and squirrels and deer and grassy fields, and load a year of this scene into the glass, and then sell it to people who live next to dirty brick walls or ugly empty lots, and those people could install the slow glass in their windows and have beautiful scenery, until it all worked its way out of the glass.
This is a great idea ! If you possibly can, find and read the sci-fi short story "Light of Other Days" written by Bob Shaw, published in Analog Science Fiction in 1966. It's all about this exact type of glass. I read this story in 1966 and I never forgot it ! (Not yet anyway.)
Answer:
v = 54m/s
Explanation:

a = 7m/s²
u = 12m/s
t = 6s
7 = (v-12)/6
v - 12 = 42
v = 54m/s
(Correct me if i am wrong)
I’d think the answer would be C. i’m just kinda guessing but my thought process is this (as simply as i can put it because physics is confusing):
so for example say you throw a ball across a flat surface. inertia is what keeps the ball rolling straight in a line, so unless you were to maybe put your hand in front of the ball or something, it would just go straight forever.
this is what happens with the planets. they go in a straight line, but since there’s gravity, the planets are also being pulled towards the sun. so gravity and inertia are why the planets orbit in the circle pattern they do. so when we remove inertia, we’re removing the state in which the planets keep going straight while being pulled towards a center point (the sun). this causes gravity to be the only factor in the planets orbiting. so that being said, the planets would just be pulled towards the sun. :)
Therefore, if the block moves from its position of maximum spring stretch to maximum spring compression in 0.25 s, the time required for a full cycle is twice as much; T = 0.5 s.