Physics Test 2

suppose that Velma's spaceship is 100 m long and 10 m tall [from bottom to top] as measured by Velma. how long and how tall is her spaceship as measure by mort, if she passes him at 90% of light speed?

about 43m long and 10m tall

a real experiment, analogous to the 'twin paradox' has actually been done in order to check the predictions of einstein's relativity. in the experiment,

an atomic clock took a trip on a jet plane, while an identical clock stayed on the ground

talk-radio station KOOK is at approximately 90 megahertz on the radio dial. this means that KOOK broadcasts

an electromagnetic wave whose wavelength is 90x10^6 vibrations per second

the 1986 susan solomon expedition

confirmed that CFCs are causing ozone depletion over Antarctica

Earth's magnetism arises from

electric currents in Earth's interior

is a fuel-cell vehicle properly described as a 'heat engine'?

no, because it converts chemical energy directly to electric energy

does the growth of a leaf violate the law of entropy, and why or why not?

no, because the increase in the entropy of the radiation passing through the leaf is greater than the decrease in the entropy of the leaf itself

a battery's 'voltage' is

the amount of energy it gives to each coulomb of electrical charge

A system's 'entropy' is

the amount of microscopic disorganization in the system

einstein believed that the principle of relativity should apply to maxwell's theory of electromagnetism. which basic principle or law did this lead einstein to propose

the constancy of light speed

according to the 2nd law of thermodynamics

the entropy of all the participants in any physical process cannot decrease

the 'atomic number' of an element that appears in the periodic table of elements represents

the number of protons in the nucleus of an atom of that element

which one of the following is the correct statement regarding the resistance?

the resistance of a wire is directly proportional to the length of the wire

a charged rod carrying a negative charge is brought near 2 spheres that are in contact with each other but insulated from the ground, if the 2 spheres are then separated, what kind of charge will be on the spheres?

the sphere near the charged rod becomes positive and the other becomes negative

suppose you photographed Earth's dark side from space, using ultraviolet-sensitive film, and using infrared-sensitive film, what would you expect to see in the photo?

the ultraviolet photo would show only artificial sources such as streetlights, while the infrared photo would show radiation coming from all over Earth

suppose that individual wave crests from either source A or source B alone are 5 mm above the level of the undisturbed water. then the displacement of the water [above or below the level of the undisturbed water] at the point marked 'x' [with the arrow pointing toward it] is

-10mm

as measured by Velma, her spaceship has a mass of 10,000 kg and a length of 100 m. she moves at 80% of light speed relative to mort. according to mor's measurements, the mas and the length of her spaceship are

16,500kg and 60m

your radio is tuned to 98 MHz on the FM dial. if the speed of electromagnetic wave is 300,000km/s, what electromagnetic wavelength is your radio receiving?

306cm

a large coal-fired electric generating plant burns about 1000kg [one tonne] of coal every 10 seconds, how much of the tonne goes into producing electric energy?

400kg

mort, who is standing on the ground, throws a ball at 20 m/s westward as measured by him. what is the ball's velocity relative to Velma, who is in a train moving eastward past mort at 70 m/s?

90m/s westward

in which of the following processes does the system's rest mass change?

a rubber ball is squeezed

two brief waves or 'pulses' are sent down a rope, in opposite directions, as shown in the figure. pulse a is 1 cm in height, and pulse b is 2 cm in depth. when they meet, they will create

a disturbance 1 cm deep

according to einstein's mass-energy relation,

a heated object has slightly greater mass than the sam object when it was cooler and a stretched rubber band has slightly greater mass than the same rubber band when unstretched

what uses thermal energy to do work?

a hot air balloon

a neutral atom loses one of its electrons. it is then

a positive ion

nuclear and fossil fuel generating plants differ in their need for

a smoke stack

before einstein, scientists thought that the substance that was 'waving' when a light wave was transmitted was

ether

when the inside of a refrigerator is cooled how does thermal energy flow, and is assistance required?

flows from cold to hot. since this is against the normal flow of thermal energy, outside assistance is required

how do we know whether or not global warming is caused by humans?

from computer calculations that 'predict' 20th-century temperatures based on natural variations, then on human-caused variations, and then on a mix of natural and human variations; the actual historical measurements then show that only natural variations are important

which part of the electromagnetic spectrum has the shortest wavelength?

gamma

electrical and gravitational forces follow similar equations with one main difference:

gravitational forces are always attractive but electrical forces can be attractive or repulsive

which type of generating plan tis more energy efficient, steam-electric or hydroelectric?

hydroelectric, because it is not a heat engine and so is not restricted by the 2nd law of thermodynamics

if you drop a coin inside a car that is slowing down, the coin will land

in front of the drop point

when the current through a resistor is increased by a factor of 4, the power dissipated by it

increases by a factor of 16

the CFC propellants used in aerosol cans are chemically inert gases. this inertness leads to problems with stratospheric ozone because

inert gases can drift upward for great distances without being broken down by the atmosphere

a fundamental physical reason for the bicycle's high efficiency as a transportation device is

it is a wheeled vehicle and it is not a heat engine

when you send a wave pulse down a rope or slinky, it eventually dies out. what has become of the energy?

it was transformed into elastic energy

a meter stick having a rest mass of 1 kg moves past you. your measurements show it to have a mass of 2 kg and a length of 1 m. how is the stick oriented, as observed by you?

perpendicular to its direction of motion

when the distance between the 2 charges is doubled, the force between them is

reduced by a factor of 4

suppose you charge 2 transparencies by rubbing and then hold them near each other but not touching, regarding the electric and magnetic forces they exert on each other

they will exert electric forces but not magnetic forces

one possible feedback effect of global warming that could 'run away' unpredictably is

warming causes methane to be released from the ocean floor, causing further warming

are small ripples sent out across the surface of a lake truly 'waves', as that word is used in physics?

yes, because the water itself doesn't go anyplace but simply oscillates up and down