Answer:

Explanation:
Initial speed of the mobile = 3.2 m/s
Final speed of the mobile = 5.2 m/s
Time, t = 8 s
We need to find the acceleration of the mobile. It can be given by the change in velocity divided by time. So,

So, the acceleration of the mobile is
.
Answer:
Velocity of rock fall collision, v = 13.21 m/sec
Explanation:
Detailed explanation given in the attached document.