A 'moving sidewalk' in an airport terminal moves at 1.0 m/s and is 35.0 m long. If a woman steps on at one end and walks at 1.5 m/s relative to the moving sidewalk, how much time does it take her to reach the opposite end if she walks (b) In the opposite direction?

Video transcript

Welcome back everybody. We have a walker later in an airport. So a walk later is simply just one of those kind of runways where if you step on it, you can kind of just stay still and it will move you down fast. Now we are told that this walker later is m and it has a speed relative to the earth of 0.9 m per second. Now, just real quick. This is gonna help us out actually going to designate the right direction as our positive direction, so this is going to be positive 0.9 m per second. Now we are told that a boy is going to start from the other end of the walker later and actually run against the direction of the walker Later speed and we are told that his velocity relative to the walker later Is negative 2. m/s. And we are asked to find how much time it takes for him to reach the other side of the Walker later in order to find our time. We are actually going to need to find the boy's velocity relative to the earth. So we are going to have that the boys philosophy relative to the earth is equal to the velocity of the boy relative to the walker later plus the velocity of the walker later relative to the earth, which if you think about conceptually makes sense. You're gonna have whatever speed you have of the walk later plus say you're sprinting in the right direction, that speed or if you're sprinting in the wrong direction plus that speed. So we are going to use this formula and we have our values. So let's go ahead and plug some of those values in. So we have that The velocity of the boy relative to the earth is equal to well, velocity of the boy relative to the Walker later negative 2. Plus velocity of the Waka later relative to the Earth, which is equal to negative two m/s. Now that we have this velocity, we can use the notion that we know that distance is equal to velocity times time to figure out our time. I'm gonna go ahead and divide both sides by our velocity, giving us the useful equation that our time is equal to the distance covered, divided by velocity. Once again we have these values. So let's go ahead and plug those values in. We have that our time T is equal to the distance covered. Well, we are told that the walk leader is 20 m long, but if you remember earlier, I designated the right direction as the positive direction. So the fact that the boy is traveling this way, he's going to cover a distance of negative 20 m. Now we also know the boys philosophy relative to the Earth. So that's what we're going to plug in for V. And then plugging this into our calculator. We get that this is 10 seconds or responding to our answer choice of B. Thank you guys so much for watching. Hope this video helped. We will see you all in the next one.