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Kinematics - Identifying and describing types of motion

  1. Mar 10, 2016 #1
    1. The problem statement, all variables and given/known data
    upload_2016-3-11_0-3-36.png

    a) Calculate the time per mode of transport of the lettuce from each starting point.
    b) calculate the total time required for each complete journey of the lettuce from its origin to Barrie
    c)
    upload_2016-3-11_0-5-37.png
    d)
    upload_2016-3-11_0-6-6.png

    e)
    upload_2016-3-11_0-6-29.png

    2. Relevant equations
    time = distance / speed or t = d/v

    3. The attempt at a solution

    a) and b)
    - for a) to calculate time per mode of transport, i divided the partial distances by the average speed
    - for b) to calculate the total time to reach the final destination, i divided the total distance with the average speed
    please tell me if this is correct.
    upload_2016-3-11_0-9-54.png

    c) this is the one i am having a hard time with, i am doing an online course so i have no help at all. If you could explain what im supposed to do for c) to help me get started, that would be greatly appreciated.


    d) please tell me if this is correct
    Route 1. Fuel consumed = (31 km) x (30 L / 100 km) = 9.3 L

    Route 2. Fuel consumed = (63 km) x (1.2 L / 100 km) = 0.76 L

    Route 3. Fuel consumed = (81 km) x (30 L / 100 km) = 24 L

    Route 4. Fuel consumed = (2279 km) x (3.5 L / 100 km) = 80 L

    Route 5. Fuel consumed = (81 km) x (30 L / 100 km) = 24 L

    e) please tell me if im right here.
    Considering that each shipment of lettuce is priced at the same value, I would chose to purchase the lettuce
    that travels the least distance (which would be the first route of lettuce). Since the lettuce travels less distance, the lettuce would be fresher, and of higher quality. It consumes a small amount of fuel (only 9.3 L) and does not produce a great amount of carbon dioxide emissions. Even though Route 2 consumes less fuel (0.76 L), it still has a longer distance to travel, meanin the lettuce will not be as fresh.
     

    Attached Files:

  2. jcsd
  3. Mar 11, 2016 #2

    Samy_A

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    For b): the way you calculate b) is not correct. Think about it: how long does a journey take that consist of two legs?

    For c): as it is stated, carbon dioxide emissions are (apparently) only dependent of the mode of transport, not the distance or time. That should make it easy to calculate the carbon dioxide emissions for each partial route, and then, by adding up these results, for each route.

    For d): you have calculated the fuel consumed on each partial route. You still have to calculate the average fuel consumption for each of the three routes.
     
    Last edited: Mar 11, 2016
  4. Mar 11, 2016 #3
    Can you give me an example for b) and c). I don't really understand what your trying to say
    for c) would I multiply the amount of carbon dioxide emissions with each partial distance.
    and for b) i don't understand what you mean by two legs??
     
  5. Mar 11, 2016 #4

    Samy_A

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    For b):
    Let's take the last route, from Solano CA to Barrie.
    The first part of the route (by plane) takes 152.2 minutes. The second part (by truck) takes 54 minutes. How long does the whole route take? Do you think that the answer you gave, 162.6 minutes, makes sense?

    For c):
    It doesn't say that the given emission rate is per kilometer. I think you have to add the give carbon dioxide emissions for each partial route (that is: 0.01 tons for a truck/train partial route, 1.08 tons for a plane partial route).
     
  6. Mar 14, 2016 #5
    thank you, i understand what you mean with part b)
    for part c) however, could you give me an example like you did with b)
    i
     
  7. Mar 14, 2016 #6

    Samy_A

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    For c, it is stated:
    upload_2016-3-11_0-5-37.png
    Now imagine a route that consists of 3 segments (=partial routes): one by plane, one by train and one by truck.
    For the first segment, by plane, the carbon dioxide emission is 1.08 tons.
    For the second segment, by train, the carbon dioxide emission is 0.01 tons.
    For the third segment, by truck, the carbon dioxide emission is 0.01 tons.
    What would be the total carbon dioxide emission for the three segments taken together?
     
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