- #1

losbellos

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Hej Guys,

I have seen on wikipedia, that power = Force x velocity, and this is fine but when they explain the same for circular moving force then they use power = Force (x arm) x Angular velocity (rads/sec). This cannot be, the velocity actually cannot be represented by only angular velocity, it needs the radius as well. For example distance = velocity x time = angular velocity * radius * time. So in this way the equation power = Force x velocity (for linear moving force) and for circular moving force the power will be = arm x force x angular velocity x radius .. in circular considering that the force is always perpendicular to the arm. If not then power would be > force x sin (Angle of force-arm) x arm x angular velocity x radius.

example considering the force and velocity as a point on a circle or a line...

radius = 10m

circle circumference = 62.83m

81 degrees/sec=1,4137 rads/sec=14.13675 m/s

powerL = force * vel = 100N * 14.13675 = 1413.675 watts

powerC = force * angular velocity * radius = 100N * 1,4137 rads * 10.0m = 1413.7 watts

so out of calculation error PowerC = PowerL

angular velocity != velocity so even in rotational systems it cannot be used alone without the radius. This way the power = torque x angular velocity is not true. To prove this like above one maybe divide the circle to line segments where the a value = force x arm x velocity x distance can be calculated for each segments, considering the torque, and these segments added will be much different from the torque x angular speed (rads/sec) x distance segments together. Naturally there will be some difference based on the number of segments. The more segments the closer it will be. Again torque x velocity != torque x angular velocity (rads/sec). The result is only same if the other equation is power = force x arm x angular velocity x radius = torque x angular velocity x radius.Am I right?

Thx.

I have seen on wikipedia, that power = Force x velocity, and this is fine but when they explain the same for circular moving force then they use power = Force (x arm) x Angular velocity (rads/sec). This cannot be, the velocity actually cannot be represented by only angular velocity, it needs the radius as well. For example distance = velocity x time = angular velocity * radius * time. So in this way the equation power = Force x velocity (for linear moving force) and for circular moving force the power will be = arm x force x angular velocity x radius .. in circular considering that the force is always perpendicular to the arm. If not then power would be > force x sin (Angle of force-arm) x arm x angular velocity x radius.

example considering the force and velocity as a point on a circle or a line...

radius = 10m

circle circumference = 62.83m

81 degrees/sec=1,4137 rads/sec=14.13675 m/s

powerL = force * vel = 100N * 14.13675 = 1413.675 watts

powerC = force * angular velocity * radius = 100N * 1,4137 rads * 10.0m = 1413.7 watts

so out of calculation error PowerC = PowerL

angular velocity != velocity so even in rotational systems it cannot be used alone without the radius. This way the power = torque x angular velocity is not true. To prove this like above one maybe divide the circle to line segments where the a value = force x arm x velocity x distance can be calculated for each segments, considering the torque, and these segments added will be much different from the torque x angular speed (rads/sec) x distance segments together. Naturally there will be some difference based on the number of segments. The more segments the closer it will be. Again torque x velocity != torque x angular velocity (rads/sec). The result is only same if the other equation is power = force x arm x angular velocity x radius = torque x angular velocity x radius.Am I right?

Thx.

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