Un carrito con un cañón accionado por resorte dispara verticalmente una esfera metálica como se observa en la figura (considere el suelo como referencia y que

la bala se libera desde el suelo). Si la rapidez inicial vertical de la esfera es 5.0 m/

s y el cañón se mueve horizontalmente a una rapidez de 0.75 m/s, a) ¿a qué

distancia del punto de lanzamiento la esfera vuelve a caer en el cañón, y b)

esperaría usted que la bala tuviera un movimiento acelerado en el eje horizontal

si el cañón estuviera acelerando al momento de ser lanzado?

Comedians like to joke that the reason we haven’t been visited by intelligent life from elsewhere in the universe is that aliens have been monitoring earth’s broadcasts of intellectually embarrassing tv programs, like gilligan’s island, fear factor, the jersey shore, and the jerry springer showand so consider us far too primitive to merit a visit. let’s check the assertion that aliens could have been receiving them. tv programs are broadcast at a frequency of about 100mhz with about 100kw of total power in 30frames per second, which emanatesroughly uniformly in all directions. assume that interstellar space transmits these broadcasts without attenuation. no matter how smart they are, aliens would require at least one photon per frame to interpret our signals. findthe number of photons per unit time per unit area reaching a receiver on a possible planet in the nearest star system, which is about 4 light-years away (a light-year is the distance light travels in a year). if aliens aimed a receiver or detector directly at earth, how big (in diameter) would it have to be to receive a photon per frame

What will a positive and a negative charge do if they are separated from each other?

Global warming will produce rising sea levels partly due to melting ice caps but also due to the expansion of water as average ocean temperatures rise. to get some idea of the size of this effect, calculate the change in length of a column of water 1.00 km high for a temperature increase of 1.00ºc. note that this calculation is only approximate because ocean warming is not uniform with depth. (answer in ×10^{-3} −3 m)