Answers:
a. Change in acceleration
b. Not change in acceleration.
c. Not change in acceleration.
d. Change in acceleration
Explanation:
Let's begin by explaining what acceleration is:
Acceleration is initially defined as the variation of Velocity in time :
However, we cannot forget acceleration is a vector quantity as well (like velocity) and as a vector it has magnitude and direction.
So, when one of these aspects changes (or both) acceleration changes as well.
In other words: A change in acceleration implies the change in velocity, or a change in direction, or both.
Having this clear, we can identify the statements that describe a change in acceleration:
a. A car stopped at a stop sign.
<u>Change in acceleration, s</u>ince the car changed its velocity.
b. A boat traveling east at 10 knots.
<u>
Not a change in acceleration</u>, since the boat is travelling at a constant velocity and is not changing its direction.
c. An airplane traveling north 600 miles per hour.
<u>
Not a change in acceleration</u>, since the airplane is travelling at a constant velocity and is not changing its direction.
d. A person running at 5 meters/second along a curving path
Change in acceleration, since the person is changing its direction in the curving path.