Asingle-engine helicopter has two rotors; a main rotor and a tail rotor. the main rotor has a diameter of 14.4 m and rotates at the rate of 450 rev/min while the tail rotor with a diameter of 1.6 m rotates at 4100 rev/min. what are the speeds, in m/s, of the tips of each rotor? main rotor speed m/s tail rotor speed m/s

Apositive rod is placed to the left of sphere a, and the spheres are separated. which best describes the spheres? sphere a is negative and sphere b is positive because protons from sphere a are attracted to the rod and move to sphere b. sphere a is negative and sphere b is positive because electrons from sphere b are attracted to the rod and move to sphere a. sphere a is positive and sphere b is negative because electrons from the rod move to sphere b and protons then move to sphere a. sphere a is positive and sphere b is negative because protons move from sphere b to the rod and also to sphere a.

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Amoving electron has kinetic energy k1. after a net amount of work w has been done on it, the electron is moving one-quarter as fast in the opposite direction. (a) find w in terms of k1. (b) does your answer depend on the final direction of the electron's motion?