The head of a grass string trimmer has 100 g of cord wound in a light, cylindrical spool with inside diameter 3.00 cm and outsid
e diameter 18.0 cm as shown in the figure below. The cord has a linear density of 10.0 g/m. A single strand of the cord extends 16.0 cm from the outer edge of the spool. (a) When switched on, the trimmer speeds up from 0 to 2 250 rev/min in 0.230 s. What average power is delivered to the head by the trimmer motor while it is accelerating? W (b) When the trimmer is cutting grass, it spins at 1 915 rev/min and the grass exerts an average tangential force of 8.80 N on the outer end of the cord, which is still at a radial distance of 16.0 cm from the outer edge of the spool. What is the power delivered to the head under load?
2 answers:
You might be interested in
Light behaves like a wave, and the different colors we perceive are the result of light hitting our eyes at different <em>wavelengths</em>. The air molecules in our atmosphere scatter this visible light, with a "preference" towards light of shorter wavelengths -- blue and violet light. Light of longer wavelengths (green, yellow, orange, red), doesn't pass through to us as visibly until later in the day, when the sun's light has more atmosphere to pass through before it reaches our eyes. The blue light becomes so scattered by the air molecules in its way at this point that we're finally able to see those yellows and reds coming through on our end.
