0.4823 m/s
The initial velocity u1 of the ball=0
From the law of conservation of linear momentum.
m1u1+m2u2=m1v1+m2v2
(160×0)+(170×u1)=(160×0.3)+(170×0.2)
u1=0.4823m/s
Good morning.
We see that

The magnitude(norm, to be precise) can be calculated the following way:

Now the calculus is trivial:
The reason why Lake Jackson disappeared is A. opening of a sinkhole.
Pollution, high atmospheric temperature, and absorption of water by the land aren't enough for an entire lake to disappear, however, a sinkhole may contribute to that. There are two major depressions (sinkholes) in this lake in Florida, and they even have their own names - Porter Sink and Lime Sink.
Whan object is at equilibrium, then the forces are balanced. Balanced is the key word that is used to describe equilibrium situations.