Un treno si muove per un certo tratto rettilineo con moto uniformemente accelerato (a = 15 m/s^2). Un oggetto di massa m = 2,0 kg rimane in quiete nonostante l'accelerazione del treno grazie all'attrito con il pavimento. Quanto vale il modulo della forza d'attrito?

Is it possible to use the energy from two atoms colliding to create a clean burning lasting fuel source with a large amount of force? is it also possible to harness that energy from the two atoms colliding to create a clean energy source that will last for years from just two atoms colliding. is there a possibility to control and store that energy for years but slowly let the energy out enough to power cities cheaper and faster.

In the first law of thermodynamics, triangle e=q-w, what does q stand for

Asmall object with mass 0.200 kg swings back and forth on the lower end of a light rope that is 3.00 m long. the upper end of the rope is attached to the ceiling. as the object swings through its lowest position, where the rope is vertical, the speed of the object is 5.80 m/s. at this point in the motion, what is the tension in the rope? (use g = 9.80 m/s2.)