The principal advantage of ac power over dc power is that
A) more energy is dissipated during transmission.
B) ac voltage oscillates while dc voltage does not.
C) ac voltage can be transformed via conventional transformers.
D) ac circuits multiply power more easily.
E) ac circuits are safer.
About 40 J is required to push a crate 4 m across a floor. If the push is in the same
direction as the motion of the crate, the force on the crate is about
A) 4 N.
B) 10 N.
C) 40 N.
D) 160 N.
A bullet is fired horizontally with an initial velocity of 300 m/s from a 20-m high tower.
If air resistance is negligible, the bullet hits downrange about
A) 200 m.
B) 300 m.
C) 400 m.
D) 500 m.
E) 600 m.
Conducting materials are composed of atoms with
A) strong cohesive forces between them.
B) loose outer electrons.
C) excess neutrons compared with protons.
D) vastly more charge than insulators.
Helium was first discovered in the
A) laboratory.
B) upper atmosphere.
C) Sun.
D) island of Helios, in Greece.
E) byproducts of nuclear fusion.
Aluminum has a specific heat capacity more than twice that of copper. Place equal
masses of aluminum and copper wire in a flame and the one to undergo the fastest
increase in temperature will be
A) copper.
B) aluminum.
C) both the same
Heisenberg’s uncertainty principle is
A) noticeable only for submicroscopic particles.
B) a fundamental principle in quantum mechanics.
C) predominant in the atomic domain.
D) all of the above
E) none of the above
A coulomb of charge flowing in a bulb filament powered by a 6-volt battery is provided
with
A) 6 ohms.
B) 6 amperes.
C) 6 joules.
D) 6 watts.
E) 6 newtons.
The Sun is not seen as yellow-green because
A) it is not yellow-green.
B) it is small part of a mixture of other colors in sunlight.
C) its brightness is only slightly greater than the other colors.
D) our vision is not adapted to yellow-green.
Both black and white road surfaces absorb sunlight. The warmer road surface at the end
of a sunny day is the
A) black surface.
B) white surface.
C) neither of these
As a balloon rises higher and higher into the atmosphere its
A) volume decreases.
B) density increases.
C) weight increases.
D) mass decreases.
E) none of the above
Two charged particles repel each other with a force F. If the charge of one of the
particles is doubled and the distance between them is halved, then the force will be
A) F.
B) 2 F.
C) F/2.
D) F/4.
E) none of the above
The frequency of a certain wave is 10 hertz and its period is
A) 0.1 second.
B) 10 seconds.
C) 100 seconds.
D) none of the above
If you toss a coin straight upward while in a train moving at constant velocity, the coin
will land
A) as if you were at rest.
B) in front of you.
C) in back of you.
A soda-pop can containing only steam is placed top downward in a pan of water. Whap!
The can is dramatically crushed by atmospheric pressure. The reduced pressure inside
the can is due to
A) contact with the relatively cooler water.
B) sudden slowing of the air and steam molecules inside.
C) condensation of steam inside.
D) reduced internal energy.
E) rapid conduction of heat to the relatively cool water.
When we apply the Lorentz factor γ to length contraction, we
A) multiply by γ as in the equation for time dilation.
B) multiply by the reciprocal of γ
C) find it does not apply.
Sound travel fastest in
A) water vapor.
B) water.
C) ice.
D) steam.
E) all of the above
The force on a dropped apple hitting the ground depends upon
A) the speed of the apple just before it hits.
B) the time of contact with the ground.
C) whether or not the apple bounces.
D) all of the above
When an electron de-excites from the third quantum level to the second, and then to the
ground state, two photons are emitted. The sum of the emitted frequencies equals the
frequency of the single photon that would be emitted if de-excitation were from the
third to
A) the second level.
B) the ground state.
C) any other level.
D) none of the above
Optical fibers are commonly used by
A) surgeons.
B) mechanics.
C) engineers.
D) aviators.
E) all of the above
Which temperature scale has the smallest sized degrees?
A) Fahrenheit
B) Celsius
C) Kelvin
D) none of the above
To catch a fast-moving ball, you extend your hand forward before contact with the ball
and let it ride backward in the direction of the ball’s motion. Doing this reduces the
force of contact on your hand principally because the
A) force of contact is reduced.
B) relative velocity is less.
C) time of contact is increased.
D) time of contact is decreased.
E) none of the above
Light from a lit match originates with accelerating
A) electrons.
B) protons.
C) neutrons.
D) all of the above
Two charged particles held close to each other are released. As they move, their speeds
increase. Therefore, their charges have
A) the same sign.
B) opposite signs.
C) either of these
D) need more information
The winner in a tug-of-war exerts the greatest force on
A) the opponent.
B) his or her end of the rope.
C) the ground.
The ideal efficiency for a heat engine operating between the temperatures of 227oC and
27oC is
A) 20%.
B) 25%.
C) 40%.
D) 88%.
E) none of the above
A black hole is
A) an empty region of space with a huge gravitational field.
B) at the center if all stars.
C) the remains of a giant star that has undergone gravitational collapse.
If the part of an iceberg that extends above the water were suddenly removed, the
A) iceberg would sink.
B) buoyant force on the iceberg would decrease.
C) density of the iceberg would change.
D) pressure on the bottom of the iceberg would increase.
E) none of the above
Terrestrial radiation is
A) emitted by Earth.
B) emitted by the Sun.
C) both of these
D) neither of these
The finding that electrons occupy discrete orbits in an atom was first explained by the
A) quantization of electric charge.
B) small mass of the electron.
C) circumference of each orbit being an integral multiple of an electron wavelength.
D) none of the above