Calculating Time on a Moving Sidewalk

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In summary, Lance takes 167 seconds to get down the gall on the moving sidewalk. If he walks while on the sidewalk, it will take him 79 seconds.
  • #1
waldvocm
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Lance takes 167 seconds to get down the gall on the moving sidewalk. While walking (not on the moving sidewalk) it took him 88 seconds. If he walks while on the sidewalk how long will it take him.

I came to the answer to easily so I am not sure if I did it right or if I am missing something

I just took the time it takes him standing on the moving sidewalk and subtracted the time it takes him to walk, not on the moving sidewalk.

My answer is 79 seconds while walking on the moving sidewalk. Is this correct? It seems too easy!
 
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  • #2
Quite often your intuition works when the equations are linear, but not in this case! You must use the formula for motion at constant speed and figure it out. Don't worry about not knowing the distance - just leave the "d" in and it will cancel out in the end.
 
  • #3
hmmmm...would this require me to know the velocity as well? I am struggling to figure out which equation you mean.
 
  • #4
For constant velocity motion, use d = v*t.
If you want an expression for the velocity, just solve the equation for v. The result will have a d in it, but that's okay - d cancels out in the end when you find the time for the guy on the moving sidewalk.

I forgot to suggest you try out your intuition on some cases. For instance, you could say "what if the walker also takes 167 seconds?" In that case your intuitive calculation would suggest a time of zero for the combined motion, which is impossible!
 
  • #5
I have the equations

d1=v(167) standing on the moving sidewalk
d2=v(88) walking off of the moving sidewalk d1=d2

v(167)=v(88)

I don't know where to go here

d3=v*t3
 
  • #6
Better make that
d=v1(167) standing on the moving sidewalk
d=v2(88) walking off of the moving sidewalk
d = v3*t3 walking on the moving sidewalk
because the d's are the same and the v's are different.

You know something about that v3, too! Notice that and you'll have one less variable and it will be possible to solve for t3.
 
  • #7
v3=88v-167v

v3=79v

Ha that brought me back to my original thinking!

I don't know I am really confused
 
  • #8
v3=88v-167v
says a velocity is equal to a distance - no good!

Say you have a slidewalk moving at 5 km/h and you run at 10 km/h on it. How fast will you be going?
 
  • #9
15km/h

So, do I add the velocities?

v1+v2=v3

d/167+d/88=d/t3
 
  • #10
Excellent! Cancel those d's and you can calculate your t3.
 

What is a moving sidewalk?

A moving sidewalk, also known as a travelator or moving walkway, is a horizontal conveyor belt used to transport people across short or long distances within an airport, train station, or other public space.

How does a moving sidewalk work?

A moving sidewalk is powered by electric motors that turn a series of rollers, creating a continuous loop of belt. The belt moves at a constant speed, typically between 0.5 to 1.5 meters per second, allowing people to walk on it and be transported to their destination.

What is the purpose of a moving sidewalk?

The main purpose of a moving sidewalk is to make it easier and faster for people to navigate through large public spaces. It helps reduce the time and effort required to walk long distances, especially for those with heavy luggage or mobility impairments.

How does time on a moving sidewalk differ from time on regular ground?

Time on a moving sidewalk is relative to the speed of the belt. For example, if a person walks on a moving sidewalk at a speed of 1 meter per second, their relative time is the same as if they were walking on regular ground at the same speed. However, if they stand still on the moving sidewalk, their relative time is faster compared to standing still on regular ground.

Does time on a moving sidewalk affect the laws of physics?

No, the laws of physics remain the same whether a person is on a moving sidewalk or on regular ground. However, the speed of the moving sidewalk may affect a person's perception of time and distance due to their relative motion.

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