practice

  1. A supertanker doesn't come with brakes. Using engines alone, it takes a loaded supertanker 13 km (8 miles) to stop. A typical vessel of this class has a gross mass of about 150 million kilograms and a cruising speed of 50 kph (30 mph). Determine …
    1. the average stopping force applied to the ship and
    2. the average power dissipated by stopping it.
  2. Write something else.
  3. Write something different.
  4. Write something completely different.

conceptual

  1. Is it possible for a motorcycle to have more kinetic energy than a truck?

numerical

  1. The Enhanced Fujita Scale is a system implemented by the National Weather Service in the US to rank the intensity of tornadoes. EF Scale values are assigned based on three second wind gust speeds. These speeds are estimated (not measured) from observed dammage. EF Scale numbers are often reported by the media.
     
    Operational Enhanced Fujita Scale
      three second gust  
    scale (mph) (m/s) typical damage
    EF0 65-85 29-38 Light:
    Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged.
    EF1 86-110 38-49 Moderate:
    Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off roads.
    EF2 111-135 50-60 Considerable:
    Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.
    EF3 136-165 60-74 Severe:
    Roofs and some walls torn off well-constructed houses; trains overturned; most trees in forest uprooted; heavy cars lifted off the ground and thrown.
    EF4 166-200 75-89 Devastating:
    Well-constructed houses leveled; structures with weak foundations blown away some distance; cars thrown and large missiles generated.
    EF5 > 200 > 200 Incredible:
    Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 meters; trees debarked; incredible phenomena will occur.
    Source: Online Tornado FAQ, Storm Prediction Center, National Weather Service
     
    How many times more intense is …
    1. an EF2 than an EF1 tornado,
    2. an EF5 than an EF4 tornado,
    3. an EF5 than an EF1 tornado?