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1: Looking
out the window oneday after a snow shower, Larry asked his father how the birds could sit
on the wet high voltage power lines without being electrocuted. His dad correctly
explained that:
a: All high -voltage
lines have an insulated cover that prevents electric shocks.
b: An enzyme in the
birds claws blocks shocks.
c: The birds donot
touch anything directly connected to the ground.
Answer: c.
An electric current won't flow until a circuit is
completed. A bird on high voltage line is safe unless, for example, it spreads its wings
and brushes against a nearby tree, which would creat a path for the electric current to
flow through the bird to the ground, completing the circuit and killing the bird. An
insulator, prevents the current from passing through the pole tothe ground. |
2: Benjamin's
surervisor at a canning company asked him to sort larger blueberries from the smaller
ones. Benjamin exparimented by gentlyshaking a crate of berries.He discovered that the
larger berries would: a: Rise to the top
b: Sink to the bottom
c: Stay where they were
Answer: a.
Shaking the crate creates small spacesbetween and
beneath the blueberries that act like a screen. Since only small berries fit into the
smalll openings, they filter down, pushing thelarger berries to the top. The same
principle explains why gardners are often frustrated by the rocks that seem to appear from
nowhere. Mild movements in the changes, create openings that dirt and small stones drop
into, gradually pushing larger rocks to the surface. |
3: The Andersons
were finishing a picnic lunch when a thunderstorm struck. Mr. Anderson hurried his family
into the car because he knew that: a: Lightning is less likely to hit a moving
target.
b: The rubber tires effectively insulate the car.
c: The auto's steel
body leads any charge safely away from the vehicle's occupants.
Answer: c.
The steel body of the car acts as a protective
cage. the electric charge travels over the surface of the vehicle, arcking the short
distance from frame to ground, leaving the passengers inside safe.
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