If an object is traveling north at the speed of light and a light is projected south, what speed will the light travel that is projected rearward? Would it stand still or would it still travel at the speed of light toward the south?

A string of length L vibrates at its fundamental frequency. The amplitude at a point (1/4) L from one end is 6.00 .

What is the amplitude of each of the traveling waves that form this standing wave?
A string of length L vibrates at its fundamental frequency. The amplitude at a point (1/4) L from one end is 6.00 .

What is the amplitude of each of the traveling waves that form this standing wave?

here’s a little hint:
In the standing wave, the displacement of the particles of the string is given by
y(x,t) = A*sin(kx)*cos(wt).
For all the particles cos(wt) remains constant. When kx = 0, the point is node. When kx = pi/2, the point is anti node, which is at the middle of the string. At L/4, kx must be pi/4.
Now find A.

There is a dome traveling at the speed of light. And a car is inside the dome traveling at a rate of 20 km/hour. What is the speed of the car? It cannot be speed of light+20 km/hr right? Because nothing is faster than the speed of light?

Thanks!

Space probes communicate with controllers on Earth using radio waves. Suppose a probe has a radiotransmitter that operates at a frequency of 388.0 MHz when at rest relative to the observer. This probe is now wandering the solar system. The signal you pick up from the probe is shifted 4.323E+4 Hz lower in frequency than the rest frequency given above. How fast is the probe traveling and is it traveling towards or away from Earth? (assume it is either traveling directly towards or directly away from Earth. You must get boths answers correct at the same time.)

What is the minimum kinetic energy (in keV) an electron must have while traveling inside a slab of crown glass (n = 1.52) in order to create Cerenkov Radiation?

Like in movies…When traveling in outerspace, If it were possible to reach light’s speed in a spaceship, how would they avoid running straight into a blackhole, asteroid, planet, Star, or whatever?

A rope of length 3.8 meters has a mass of 1.2 kilograms. The rope is stretched so that the tension in the rope is 3.0 Newtons, and waves of wavelength 5.4 meters are seen traveling along the rope.

What is the velocity of the waves traveling on the rope?
What is the frequency of the waves on the rope?

My Optics lecturer said something about how since light travels in a vacuum, you could, potentially, have something travel faster in a different medium, one other than a vacuum.

True or false?

If Electromagnetic Radiation can travel through the vacuum of space then it can travel without a medium, but shouldn’t this be imposable? Or is it true that Electromagnetic Radiation uses the medium of existing magnetic fields, such as earths, distorting these fields much like sound waves do to air? And if so how can this have a direction of travel?

How can a person travel into the future of their original time line, what might be considered their present, given that once in the past, a divergent time line is necessary to preserve continuity? Seems that once a person travels back in time, it may be impossible to go back home.