Exam 27: Relativity

Astronaut Mark Uri is space-travelling from planet X to planet Y at a speed of 0.65 c.When he is precisely halfway between the planets,a distance of 1 light-hour from each,nuclear devices are detonated.The explosions are simultaneous in Mark's frame.What is the difference in time of arrival of the flashes from the explosions as observed by Mark?

A light source is flashing on and off with a frequency of 1 Hz.If you were to run really fast (say 80% the speed of light),with your direction of motion perpendicular to the direction of the light,you would observe the frequency of the flashing to

Free neutrons (unlike those in the nucleus of an atom)decay spontaneously into a proton,an electron,and an antineutrino.The masses of these particles are (approx. ): mn = 1.67492 × 10^-27 kg Mp = 1.67262 × 10^-27 kg Me = 9.10939 × 10^-31 kg The mass of the neutrino is zero (or nearly so).How much energy is released in this decay?

In a common rest frame,event A happens on planet A and event B occurs on planet B 100 y later.If the space time interval between these two events is 90 ly,how far apart are the 2 planets in their common rest frame?

A spaceship is moving in a straight line at a speed of 0.8 c (relative to Earth).It launches a missile that moves away from the spaceship (traveling in the same direction as the spaceship)at a speed of 0.6 c.Relative to Earth,the speed of the missile is

In their common rest frame,two stars are 90.0 ly apart.If they appear to be 68.7 ly apart to a spaceship,how fast is the spaceship moving? Express your answer in terms of c.

The star Alpha Centauri is 4.25 light years from us,so it takes its light 4.25 years to reach Earth.It is impossible,in principle,for any rocket from Earth ever to reach this star in less than 4.25 light years.

A right-angled construction frame ABC,when measured at rest,has dimensions as follows: AB = 19.00 m,AC = 10.00 m,and BC = 16.16 m.The frame is given a velocity of 0.56 c,relative to the space platform,in a direction parallel to AC.The dimensions of the moving frame are measured simultaneously by observers on the platform.In the figure,the length BC measured by these observers is closest to:

The United States is approximately 3000 mi wide as measured by people on Earth.If astronauts in a spaceship traveling at 45% the speed of light measure this distance,they will measure it to be more than 3000 mi.

Two fixed navigation beacons mark the approach lane to a star.The beacons are in line with the star and are 40 Mm apart.A spaceship approaches the star with a relative velocity of 0.30 c and passes the beacons.The passage of the ship between the beacons is timed by observers on the beacons.The time interval of the passage is closest to:

Situation 27.1 A proton (rest energy = 938 MeV)has a speed of 0.80 c. -In Situation 27.1,the momentum of the proton in kg ∙ m/s is closest to:

A particle in a 453 m-long particle accelerator is moving at 0.875 c.How long does the particle accelerator appear to the particle?

If,in a certain reference frame,an object with no unbalanced forces on it keeps moving with constant velocity,then that frame must be an inertial reference frame.

An object of mass M is initially moving at a speed of 0.999 c and collides inelastically (they stick)with another identical object that was initially at rest.After the collision,the two objects are moving with a speed

A particle has speed 0.95 c and total energy 4.8 × 10^-10 J.What is its momentum?

Adding heat to an object will increase its mass because the added heat energy is equivalent to mass.

One spaceship leaves planet X and heads toward planet Y,which is 70 ly away,as measured in the rest frame of the two planets.100 ly later (again,in the two planets' rest frame),a second spaceship leaves planet Y and heads for planet X.Calculate the space time interval between these two events.

Consider two synchronized,extremely accurate clocks.One clock is on the ground,the other is placed in a jet and flown once around the world,then taken out of the plane and compared with the ground clock.Will the clock on the jet read a time earlier than,the same as,or later than the stationary clock? Support your answer?

A person buys a SUV and discovers that it is too long to fit in the garage (the length of the SUV is 1.3 times the length of the garage).He decides to drive the SUV into the garage at a speed of 0.99 c.Which statement is true?

If you were in a spaceship traveling at a speed close to the speed of light (with respect to Earth)you would notice that