Scientist crafted the big bang theory after studying numerous galaxies and finding that most of them had red shifts. Describe what kind of theory scientists might have crafted if most of the galaxies they studied had blue shifts.

Consider a double atwood machine constructed as follows: a mass 4m is suspended from a string that passes over a massless pulley on frictionless bearings. the other end of this string supports a second similar pulley, over which passes a second string supporting a mass of 3m at one end and m at the other. using two suitable generalized coordinates, set up the lagrangian and use the lagrange equations to find the acceleration of the mass 4m when the system is released. explain why the top pulley rotates even though it carries equal weights on each side.

Select all the correct answers. which two statements are true? a moving magnetic field creates an electric field. a constant magnetic field creates an electric field. a constant electric field creates a magnetic field. a moving electric field creates a magnetic field. resetnext

What is the efficiency of an engine that does 80 j of work and exhausts 320 j of heat while taking in 400 j of heat ? a. 10% b. 20% c. 80% d. 25%