A choir made up by 100 voices (i.e. 100 singers), during the execution of a song, reaches the sound intensity of 100dB. Assuming that all singers sang with the same intensity, the sound intensity of each singer was...?
In the image below, there are two balls of mass m attached to a massless rigid metal steam, which can rotate around the point A. Give the necessary velocity to be applied in the lowest ball for the system to reach the horizontal line. Do not consider any system's energy...
A train is traveling on a horizontal and straight track, with a constant speed of 20m/s, when it begins to rain.
The rain is rigorously vertical and the mass of the water that falls over the train and after that runs vertically by it sides is 100kg per second.
(Sorry if I used any wrong term, English isn't my first language)
Be A (mass M) and B (mass m) two blocks connected to each other through an ideal wire passing through a wheel (caster), each block stays at one of the side of the wheel. If we apply a force F pointing up into...