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.
Final speed after collision with the wall

before collision the speed of ball initially

time taken for the collision

now as per the formula of acceleration we know that

now plug in all values in it


so acceleration is - 5 m/s/s for above situation
Answer:
If iron, nickle, or cobalt is an answer choice, those are the three metals that are purely magnetic.
Answer:an electrical Current can be defined as the free flow of electrons through a circuit
Explanation:
Answer: Friction is the resistance to motion of one object moving relative to another. For example, when you try to push a book along the floor, friction makes this difficult. Force: Force is essentially a push, or a pull action, that can lead to certain outcomes.