Question

The altitude of an airplane is decreasing at a rate of 42 feet per second. What is the change in altitude of the airplane over a period of 22 seconds?
A.
924 feet
B.
-64 feet
C.
64 feet
D.
-924 feet

Answer 1

Answer:

D.  -924 feet

Step-by-step explanation:

Necessary formula

For this problem, we'll need the relationship $d=vt$ where "d" is the distance traveled, "v" is the velocity the object is traveling, and "t" is the amount of time that it traveled.

Velocity Vectors

Velocity is a "vector" quantity, which has both a magnitude and a direction.  The magnitude is the speed (42 feet per second) and the direction is downward.  Collectively, the velocity is -42 feet per second.  This will address the change in altitude and signify that the change in altitude is downward.

Units

All quantities should be using units that match.

In this case, the distances provided in the answers are all measured in feet, and the speeds are measured in feet per second, so the feet match.

Also, the times are measured in seconds, and the speeds are measured in feet per second, those also match.

Substitution & solve

$d=vt$

$d=(\frac{-42\text{ feet}}{\text{second}})(22\text{ seconds})$

$d=-924 \text{ feet}$