Modern physics , Lorentz transformation In its rest frame. a source emits light in a Conical beam of width +45 -45° in frame moving toward the Source at speed v , the beam width is +30 -30° What is v?

What should the power status of a circuit be when measuring resistance with an ohmmeter?

Could we see a galaxy that is 20 billion light-years away?

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.