KW of laser required to cut through a giant redwood tree in one second?

[Flaminpyro]

From a cracker jack box :crackup:

where do you get the math for that?

 

[Teslanium]

Consider that a laser powerful enough to slice through a redwood tree would also heat and ionize the gaseous products from the cutting, if not the air itself, with resultant defocusing/degradation of the beam from thermal effects and absorption.

Perhaps a better (if not far more time-consuming method!) would be to scan the focus point of an only 10,000W laser so as to burn off layer by layer a band several inches wide which would leave room for the vaporization products to be better dissipated by wind.

T.

 

[yathern2]

Consider that a laser powerful enough to slice through a redwood tree would also heat and ionize the gaseous products from the cutting, if not the air itself, with resultant defocusing/degradation of the beam from thermal effects and absorption.

Perhaps a better (if not far more time-consuming method!) would be to scan the focus point of an only 10,000W laser so as to burn off layer by layer a band several inches wide which would leave room for the vaporization products to be better dissipated by wind.

T.

Maybe we're assuming the redwood tree is a perfect cylinder, in an absolute vacuum.

 

[TheDukeAnumber1]

Lasers can cut a wooden gear from 0.5 - in. - thick walnut hardwood at a speed of 85 in. per minute using power levels of 400 W (bottom)

85/60 = 1.417inches per second
1.417inches in metres = 0.036m per second at 0.5inch thickness
0.5inch in metres = 0.0127m thickness for laser described
6.04m / 0.0127m ..... General Sherman tree = 476x thicker than above laser tool can manage
0.036m /476 ..... Therefore instead of 0.036m/s, the 400W laser could only manage 0.0000756m/s on the tree
7.67m / 0.0000756m = 101,455x more powerful laser needed to cover 7.67m in one second
400watt*101455 = 40,582,000watt
40,582,000watt as megawatt = 40.6 megawatt

So the final conclusion.......:
40 megawatt of laser power required to slice through (and topple) a giant redwood tree in one second!

Phenol was actually pretty close with his estimate!! (off by a factor ~4).

If anyone can point to flaws in the math, please let me know!

I don't think we can assume that correlation is accurate.