Because the ball is a sphere and there's nothing that can actually stop a sphere unless you cover it with something that will actually stop it, for example like your hand.
When the velocity increases, then the acceleration will be positive and when the velocity decrease then the acceleration will be negative.
During the first hour, the velocity was 70 mph and during the seconds hour the velocity was 60 mph. Hence, the velocity decrease in the seconds hour. So, the acceleration will be negative during the second hour.
Now, during the third hour the velocity increases as it is 80 mph. Hence, the acceleration will be positive during the third hour.
Hey there friend :)
I would go with Choice A
Sorry if wrong :(
Have a Fabulous day!
I believe the answer is option C 1.8 kg•m/s to the east