How fast is the rock traveling?

A rock is twirled in a horizontal circle overhead on a string with a frequency of 30 revolutions per minute. If the radius of the circle is 35cm. How fast is the rock traveling?

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  • oubaas
    Lv 7
    2 months ago
    Favorite Answer

    period T = 1*60/30 = 2.00 sec 

    angular speed ω = 2PI/T = PI rad/sec 

    tangential speed V = ω *r = 3.1416*0.35 = 1.10 m/sec 

  • 2 months ago

    The rock covers 30 circle perimeters per minute.

    One perimeter is 2rπ so the total path is

    s = 30 * 2rπ = 60 * 35 * π = 6597 cm

    Because time for this path is 1min, the speed is also

    v = 6597 cm/min = 65.97 m/min = 1.1 m/s (rounded)

    General formula is

    v = 2 r π f

    where

    r is radius

    f is frequency

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