Scientific reasoning quiz #6

In their famous 1887 experiment, Michelson and Morley tried to measure the speed of Earth's motion through aether using perpendicular beams of light. What did the result of their experiment imply?

Earth isn't moving through aether at all.

Which law of classical mechanics was replaced by Einstein's idea that the worldline of any inertially-moving object follows a geodesic through spacetime?

Newton's first law of motion

Special relativity is incompatible with which law of classical physics?

Newton's law of universal gravitation

The moon is approximately 380,000 km away from Earth, on average, so it takes a little more than one second for its light to reach Earth. If a "shooting star" (small meteor) strikes the Earth and a large asteroid hits the moon exactly 1 second later, the spacetime interval between the meteor strike and the asteroid impact is:

Positive

Some quantities in physics depend on an arbitrarily-chosen frame of reference. For example, an object's velocity, its momentum, and its kinetic energy vary depending on which reference frame is chosen. Quantities that vary from one reference frame to another are called_________

Relative quantities.

If two events occur outside each other's light cones, the events have _ ______separation.

Spacelike

Astronauts on the International Space Station (ISS) don't feel Earth's gravitational pull, because:

The ISS is in orbit, so it is essentially free-falling toward Earth.

Which one of these objects does not follow a geodesic through spacetime, according to general relativity?

a rock lying on the ground

Which phenomenon would not occur if the "aether drag" hypothesis were correct?

stellar aberration

Imagine a rocket far away in deep space, where the gravitational pull from stars and planets is negligible. If the rocket speeds up with a constant acceleration of 9.8 m/s2, standing inside the rocket's capsule will feel exactly like standing on Earth. According to Einstein, this is no coincidence: gravity and acceleration feel the same because they are the same! The claim that gravity and acceleration are physically the same is called:

the equivalence principle

According to Einstein's special theory of relativity, all inertial reference frames agree on:

the spacetime interval (timelike, lightlike, or spacelike separation) between two events

In Einstein's famous equation E = mc2, what does the "E" represent?

the total energy an object contains.

Which scientist concluded that aether doesn't exist?

Albert Einstein

If two events occur inside each other's light cones, there is an absolute fact of the matter (all reference frames agree) about which event occurred first.

True

Most of the mass of an atom consists of potential energy from the nuclear strong force.

True

Theories of relativity in physics DO NOT support relativism, the view that there are no absolutes.

True

When an object with mass is accelerated close to the speed of light, its relativistic mass increases

True

Suppose a rocket is traveling away from the earth at 270,000 km/s (90% the speed of light). According to Einstein, if we shine a laser beam past the rocket, how fast will the beam of light be traveling in the rocket's frame of reference?

300,000 km/s (100% the speed of light

What conclusion did Newton draw from his "spinning bucket" thought experiment?

Acceleration is an absolute (non-relative) quantity.

f two events occur outside each other's light cones, there is an absolute fact of the matter (all reference frames agree) about which event occurred first.

False

According to Galilean relativity (Galileo's theory of relativity), the same laws of motion hold in all ______ reference frames.

Inertial

When the net force on an object is zero, the object's motion is_______

Inertial

In the Hafele-Keating experiment, four clocks were flown around the world on commercial airliners, first eastward and then westward. The clocks ran slower when flown eastward, and they ran faster when flown westward. Explain why.

The clock on the eastward plane ran slower as it experienced the most acceleration due to flying in the same direction the earth was rotating in. Whereas the westward clock ran faster as it stayed in a nearlt inertial refrence frame while earth rotated beneath it. The groundbase clocks ran as expected for a "stationary" clock.

If it is possible to get from one event to another traveling slower than the speed of light, the two events have _______ separation.

Timelike

Einstein's special theory of relativity implies that a spaceship traveling faster than light would also be going backwards in time: a passenger on board would see effects happen before their causes.

True

Suppose an alien spaceship were to zoom past the earth at a constant velocity close to the speed of light. Which of the following is/are predicted by special relativity? (select all that apply)

a. According to Earth's reference frame, the alien's clock is running slower than ours. b. According to the alien's reference frame, our clock is running slower than hers. c. From our perspective, the alien's meter stick is shorter than ours. d. From the alien's perspective, our meter stick is shorter than hers.

Which of the following phenomena are predicted and explained by Einstein's general theory of relativity? (indicate all that apply)

a. As light travels away from a massive object, its wavelength increases. b. Atomic clocks run slightly slower at low altitudes and slightly faster at high altitudes. c. Waves of curvature travel through spacetime itself. d. Starlight bends as it passes near the sun. e. The elliptical orbits of planets gradually precess.

In which of the following ways did Einstein's special theory of relativity differ from Lorentz's theory? (Select all that apply.)

a. Lorentzian relativity says that the aether's reference frame is the only frame in which measurements of distance and time are objectively correct; but according to Einstein, all inertial reference frames are equally valid. b. Lorentz had suggested that length contraction and time dilation are physical effects caused by an object's motion through aether; but according to Einstein, times and distances are just relative quantities which differ from one reference frame to another.

In a spacetime diagram, a curved worldline represents an object that is

accelerating

In order for one event to cause another, according to special relativity, the two events must______

occur within each other's light cones