Question

1. Identify whether the following statements describe a change in acceleration. Explain your response.

a. A car stopped at a stop sign.

b. A boat traveling east at 10 knots.

c. An airplane traveling north 600 miles per hour.

d. A person running at 5 meters/second along a curving path.

Answer 1

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 $a$ is initially defined as the variation of Velocity $\Delta V$ in time $\Delta t$:  

$a=\frac{\Delta V}{\Delta t}$  

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.

Change in acceleration, since the car changed its velocity.

b. A boat traveling east at 10 knots.

Not a change in acceleration, since the boat is travelling at a constant velocity and is not changing its direction.

c. An airplane traveling north 600 miles per hour.

Not a change in acceleration, 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.