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As soon as the ball is released from the rod, it starts going in a tangential direction. Since there are no external forces on the system, the linear momentum of the system (ball + motor) must be conserved and the motor starts moving in the opposite direction of the ball with some velocity (depending upon the masses of ball and motor), so that the linear ...


Dyson fans are NOT efficient (despite claiming otherwise). They emit about 1 gram of high-speed air for every 10 grams of air accelerated. Sounds efficient, right? No! The Dyson fan is analogous to throwing a 1kg dart at 10 m/s toward at a 9kg target sitting on ice. The resulting dart+target has a velocity of 1 m/s (momentum conservation). However, the ...

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