# How to convert Joules(kinetic energy) plot chart into watts?

How to convert Joules(kinetic energy) plot chart into watts? Anyone know how?

• Watts are Joules per second, so area under the curve. – Solar Mike Oct 4 '18 at 3:24
• @SolarMike But the area under the curve would give Joules times seconds, which seems a meaningless quantity. Using the slope of the curve would be better! – alephzero Oct 4 '18 at 8:28
• Why you don't plot it in Watts? Solidworks does plot in Watts. – Sam Farjamirad Oct 4 '18 at 10:31
• @SolarMike I think you're thinking of the other way around. To get total energy from a power plot you just integrate. – JMac Oct 4 '18 at 14:36
• Yeah; the differential is tan( angle of the curve ) or rise rate. – SF. Oct 5 '18 at 12:33

## 1 Answer

To convert a plot of J versus s to a plot of J/s vs s, take the derivative.

Here is my quick-and-dirty answer after digitizing the data.

• What software package[s] did you use here? – Chemomechanics Oct 4 '18 at 22:23
• IgorThief in Igor Pro. WaveMetrics.com. When I would have the raw data rather than image, this would be a direct one-step process that would be accurate rather than rough. – Jeffrey J Weimer Oct 4 '18 at 22:51
• @Chemomechanics my favorite tool for digitizing graphs is DataThief. It's like magic. – Carl Witthoft Oct 5 '18 at 16:53