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Mr N
Lv 5
Mr N asked in Science & MathematicsPhysics · 9 years ago

A wheel of a car of radius 21 cms is rotating at 600 RPM. What is the speed of the car in km/hr?

Update:

Hey shouldn't it be RW ( R = radius and W = angular speed )...

Because we can imagine each wheel to be rolling. And also each wheel's translational speed (RW) should be equal to the car's translational speed..

Thanks

4 Answers

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  • billrussell42
    Lv 7
    9 years ago
    Favorite Answer

    Do you mean radius is 21 cm? (cms is not correct)

    circumference is 42π cm, 1 revolution

    at 600 rev per minute that is a distance of

    42π cm/rev x 600 rev/min x 60 min/hour x 1 km/100000cm = 47.5 km/hour

  • Anonymous
    9 years ago

    Every time the tire rotates, the car will go forward by the tire's circumference.

    C=2πr

    C=42π

    Because it's traveling at 600 RPM, it travels 600(42π) cm/m, or 79168.13 cm/m

    Use conversions to get km/hr. Divide by 100,000 to get cm -> km, multiply by 60 to get m -> hr.

    Final answer is 48 km/h

  • Nightshadow
    9 years ago

    2*21*phi=131,88

    131,88/60 seconds = 2,198 cm/second * 600 = 1318,8

    1 cm/s = 0,036 kmh

    1318,8 * 0,036 = 47,4768 kmh

    I just guessed something anyways im 16 so the chance is big im wrong... only trying to help though :)

  • Douglas
    Lv 7
    9 years ago

    (21cm)(1 meter/100 cm)(1 km/1000 meters)(2π/ revolution)(600 revolutions/minute)(60 minutes/hour) = 47.5 km/hr

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