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The motor of an engine is erotating about its axis with an angular velocity of 100 rev/minute. It comes to rest in 15 s, after being switched off. Assumgn cnstant angular decelertion, calculate the number of revolutions made by it before coming to rest.


The initila ngular velocity =100 rev/minute =(10pi/)rad/s\({F}{i}\frac{{N}}{{A}}{l}{a}{n}{g}\underline{{a}}{r}{v}{e}{l}{o}{c}{i}{t}{y}={0}{T}{i}{m}{e}\int{e}{r}{v}{a}{l}={15}{s}\lt{b}{r}.{L}{e}{t}{a}{n}{g}\underline{{a}}{r}{a}{\mathcal{{e}}}\le{r}{a}{t}{i}{o}{n}{b}{e}\)alpha\(.{U}{\sin{{g}}}{t}{h}{e}{e}{q}{u}{a}{t}{i}{o}{n}\)omega=omega_0+alphtat\({w}{e}{o}{b}{t}{a}\in\alpha={\left(-{2}\frac{\pi}{{9}}\right)}{r}{a}\frac{{d}}{{s}^{{2}}}\)
The angle rotated by teh motor during this motion is
Hence the motor rotates thrugh 12.5 revolutions before coming to rest.
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