Longitud

  1. Dibuja en tu libreta la “escalera” de la longitud, con las instrucciones que te dará el profesor.
  2. Expresa las medidas en la unidad que se indica:
    1. 7,34 km en metros =
    2. 0,125 m en centímetros =
    3. 25 670 mm en metros =
  3. Change:
    1. 732 cm to metres.
    2. 410 mm to centimetres.
    3. 840 mm to metres.
    4. 1.2 metres to centimetres.
    5. 0.72 cm to milimetres.
    6. 3 m to milimetres.
  4. Fill the gaps:
    1. 125 cm = … m; 82 mm = … cm; 550 mm = … m; 2100 m = … km;
    2. 208 cm = … m; 1240 mm = … m; 34 km = … m; 3.4 m = … mm;
    3. 13.5 cm = … mm; 0.67 m = … cm; 7.03 km = … m; 0.72 cm = … mm;
    4. 0.25 m = … cm; 0.64 km = … m; 3 km = ... m; 0,75 km = ... m
  5. El diámetro de un glóbulo rojo es de 6 μ (micras). ¿Cuántos glóbulos rojos habría que juntar para hacer una fila de 1 pulgada de largo?
  6. Expresa en la unidad más adecuada la longitud de uno de tus pasos normales.
  7. Expresa en milímetros, centímetros y metros tu estatura:
    1. Yo mido ............ milímetros.
    2. Yo mido ............ centímetros.
    3. Yo mido ............ metros.
  8. Magazines are stored in piles of 100. Each magazine is 4 mm thick. Calculate the height of one pile of magazines. Give your answer in centimetres.
  9. Look at these pictures:
Glóbulo rojo
  1. The wall has nine layers of bricks. Each brick is 7.5 cm high. Each layer of mortar is 13 mm thick.
    1. Calculate the height of the wall, in centimetres.
    2. The wall is to be continued until it is at least 1 metre high. What is the smallest number of extra layers of bricks needed?

Imperial system equivalences

  • 12 inches = 1 foot
  • 3 feet = 1 yard
  • 1760 yards = 1 mile

Examples of the everyday use of imperial measures are:

  • miles for distances by road
  • feet and inches for people’s heights
  • the altitude of a plane in flight
  1. Fill the gaps:
    1. 2 feet = … inches
    2. 4 yards = … feet
    3. 2 miles = … yards
    4. 4 feet = … inches
    5. 1 yard = … inches
    6. 10 yards = … feet
    7. 60 inches = … feet
    8. 36 feet = … yards
    9. 8800 yards = … miles
    10. 1 mile = … feet
    11. 96 inches = … feet
    12. 15 feet = … yards
    13. 1 mile = … inches
    14. 15 840 feet = … miles

Conversion factors

You need to know the approximate conversions between certain imperial units and metric units.

The symbol ‘≈’ means ‘is approximately equal to’.

  • 1 inch ≈ 2.5 centimetres (trick: double plus a half). Actually, 1 inch = 2.54 cm
  • 1 foot ≈ 30 centimetres (trick: times three and add a zero). Actually 1 foot = 30.48 cm
  • 1 mile ≈ 1.6 kilometres (trick: one plus a half plus one tenth). Actually 1 mile =1.609344 km
  • 5 miles ≈ 8 kilometres. Actually 5 miles = 8.04672 km.
  1. Use the conversion factors above to find the following approximations. Note: An answer should be rounded when it has several decimal places, since it is only an approximation.
    1. 8 inches = … cm
    2. 30 miles = … km
    3. 30 cm = … inches
    4. 80 km = … miles
    5. 100 miles = … km
    6. 1 km = … yards
    7. 1 foot = … cm
    8. 1 yard = … cm
  2. Which is longer, a metre or a yard? Show your working clearly.
  3. Two villages are 40 km apart.
    1. Change 40 km into metres.
    2. How many miles are the same as 40 km?
  4. Susan is driving through a French town. The speed limit in the French town is 50 kilometres per hour. Her speed is 35 miles per hour. Is she breaking the speed limit?
  5. Calculate the percentage error we make when we use the estimations above.

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