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.
Answer: experiment data is the things you do in the experiment and the result is the answer
When discussing Newton's laws of motion, particularly Newton's third law of motion, the terms that almost everyone will use are "action" and "reaction".
You must not take this to mean that they understand what they're talking about.