Rishi is a pediatric infectious disease physician and works at Khan Academy. More free lessons at: http://www.khanacademy.org/video?v=RpbxIG5HTf4 These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. In this video David Santo Pietro explains the idea of power used in physics. Both average and instantaneous power are discussed.