Physics MCQ series - 40

Phy-Q,

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391: Ice skating is possible and practical because of a unique property of water.  Is it because:

w)  The coefficient of kinetic friction of steel on frozen water decreases with decreasing temperature

x)  Ice readily sublimes

y)  The melting point decreases with increasing pressure

z)  Ice is a good thermal insulator

ANSWER:  Y -- THE MELTING POINT DECREASES WITH INCREASING PRESSURE

392: 1 kilogram of boiling water is poured into an empty thermos whose mass is 1 kilogram and whose temperature is 25o Celsius.  No heat is lost from the thermos.  The specific heats of water and the thermos are 1 and 0.5 kilocalories per kilogram degree Celsius, respectively. Their final temperature is:

w)  50^o Celsius

x)  65^o Celsius

y)  75^o Celsius

z)  90^o Celsius

(Read: "degrees Celsius")

ANSWER:  Y -- 75o CELSIUS

393: An aluminum rod at a temperature of 100o Celsius radiates energy at a rate of 10 watts.  If its temperature is increased to 200o Celsius, at approximately what rate will it radiate energy?

w)  15 watts

x)  20 watts

y)  26 watts

z)  80 watts

ANSWER:  Y -- 26 WATTS

394: The coating on the plastic tape you use in your cassette players is

w)  Diamagnetic

x)  Paramagnetic

y)  Ferromagnetic

z)  A permanent magnet

ANSWER:  Y -- FERROMAGNETIC

395:  Which color light has the highest frequency?

w)  Green

x)  Violet

y)  Red

z)  Yellow

ANSWER:  X -- VIOLET

396:  Your Minolta camera has a 50 millimeter lens.  The 50 millimeters is the lens'

w)  Diameter

x)  Focal length

y)  Magnification

z)  Aperture

ANSWER:  X -- FOCAL LENGTH

397:  You want to put up a mirror at a blind corner in a building.  Which of the following will give you the largest field of view? Is it a:

w)  Convex mirror

x)  Concave mirror

y)  Cylindrical mirror

z)  Plane mirror

ANSWER:  W -- CONVEX MIRROR

398:  Dr. Leon Lederman and two other physicists won the Nobel prize for discovering an elementary particle.  That particle is the:

w)  Positron

x)  Meson

y)  muon

z)  Neutrino

ANSWER:  Z -- NEUTRINO

399:  Neutrinos are a subset of which of the following categories?

w)  Photons

x)  Leptons

y)  Mesons

z)  Baryons

ANSWER:  X -- LEPTONS

400:  A flywheel rotating at 5 revolutions per second is brought to rest by a constant torque in 10 seconds.  How many revolutions does the flywheel make while coming to a stop?

w)   25

x)   50

y)   75

z)  100

ANSWER:  W -- 25