Answer:
9.22 s
Explanation:
One-quarter of a turn away is 1/4 of 2π, or π/2 which is approximately 1.57 rad
Let t (seconds) be the time it takes for the child to catch up with the horse. We would have the following equation of motion for the child and the horse:
For the child: 
For the horse: 
For the child to catch up with the horse, they must cover the same angular distance within the same time t:



t = 25.05 or t = 9.22
Since we are looking for the shortest time we will pick t = 9.22 s
Answer: C
Explanation:
Find the acceleration using this kinematic equation:

Now use this kinematic equation to find the displacement:

You draw 3 circles around the stations with the size of the circle equal to the distance from the earthquake. Then you simply find where the edge circles all overlap.
Answer:
c. Case iii
Explanation:
the ball will experience the largest change in case iii