An elevator moving down passes its neighbor, an elevator moving up. their speed relative to one another is 8 m/s. what is the velocity of each elevator relative to someone standing on the first floor? assume that the elevators are traveling at the same speed, and that the upward direction is positive.

If they appear to be travelling at 8 m/s as viewed by one of them, then someone on ground floor sees what is actually happening. One is going up at 4 m/s and the other is going down at 4 m/s.

The direction matters. The answer is C.

answer

explanation

the area of a circle is calculated using the formula

or

we can use any of the above formulae to calculate the required. preferably, let us use the latter since the diameter is

we substitute the diameter into the formula to get:

this is the exact value for the area of the circle.

the correct answer is a