- #1

Matt Poirier

## Homework Statement

You are in a large store that has escalators connecting its floors. The stairs of each escalator move smoothly and steady either uphill or downhill as they carry passengers between floors.

You get off the "up" escalator on the second floor and board the "down" escalator. This escalator takes you from the second floor back to the first floor. Like the "up" escalator, the "down" escalator is 12 meters (39.4 feet) long. As before, the second floor is 4 meters (13.1 feet) above the first floor vertically. Let's continue to suppose that you weigh 600 Newtons (135 pounds-force). How much work does the "down" escalator do on you in carrying you from the second floor to the first floor?

I am confused as to whether or not the solution is positive or not. When the escalator moves you downward, doesn't it exert a force moving you downward making work positive? Or does the escalator always exert an upward force, and since you move downwards, work is negative?

## Homework Equations

Work = force * distance

## The Attempt at a Solution

-2400 joules, but I am not sure if it is negative.