PHY183-Lecture20 - Physics for Scientists&Engineers 1 1 Physics for Scientists& Physics for Scientists& Engineers 1 Engineers 1 Spring

Info iconThis preview shows pages 1–8. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: February 20, 2006 Physics for Scientists&Engineers 1 1 Physics for Scientists & Physics for Scientists & Engineers 1 Engineers 1 Spring Semester 2006 Lecture 20 February 20, 2006 Physics for Scientists&Engineers 1 2 Kinetic Energy: Summary Kinetic Energy: Summary Definition: (note: K can never be negative!) Energy unit: Work - Kinetic Energy Theorem: 1 J = 1 kg m 2 s-2 ! K " K # K = W K = 1 2 mv February 20, 2006 Physics for Scientists&Engineers 1 2 Kinetic Energy: Summary Kinetic Energy: Summary Definition: (note: K can never be negative!) Energy unit: Work - Kinetic Energy Theorem: 1 J = 1 kg m 2 s-2 ! K " K # K = W K = 1 2 mv 2 February 20, 2006 Physics for Scientists&Engineers 1 3 Work: Summary Work: Summary Work for constant force - 1d Work for constant force - 3d Work done by a variable force, 1d case Most general 3d case Work done against gravity Work done by spring force W = F ( x ') dx x x ! ' W = r F r r ' ( )• d r r ' r r r r ! W = ! 1 2 kx 2 + 1 2 kx 2 W = r F • ! r r = r F ! r r cos " F ! r W = F ! " x = F ! ( x # x ) W g = mgh February 20, 2006 Physics for Scientists&Engineers 1 4 Power: Summary Power: Summary Definition of power as the rate at which work is done Average power over a time interval Δ t Unit of power (SI) Unit of power (non-SI) Common energy unit Power for constant force P = dW dt P = W ! t 1 W = 1 J/s 1 hp = 550 ft lb/s = 746 W 1 kWh = 3.6 ! 10 6 J = 3.6 MJ P = r F • r v P = Fv cos ! Fv February 20, 2006 Physics for Scientists&Engineers 1 5 Potential Energy Potential Energy Definition: How are work, kinetic energy, and potential energy related? Potential energy, U , is the energy stored in the configuration of a system of objects that exert forces on each other. February 20, 2006 Physics for Scientists&Engineers 1 6 Gravitational Potential Energy Gravitational Potential Energy Definition of gravitational potential energy Change in gravitational potential energy Last week we calculated the work done by the gravitational force on a mass lifted to a height h=y-y : Compare the two results: U g = mgy ! U g " U g ( y ) # U g ( y ) = mg ( y # y ) W g = ! mgh ! U g = " W g February 20, 2006 Physics for Scientists&Engineers 1 7 Energy Storage Energy Storage We do work to lift a mass up to a higher elevation and leave it there, storing the work in form of potential energy...
View Full Document

This note was uploaded on 03/19/2008 for the course PHY 183 taught by Professor Wolf during the Spring '08 term at Michigan State University.

Page1 / 23

PHY183-Lecture20 - Physics for Scientists&Engineers 1 1 Physics for Scientists& Physics for Scientists& Engineers 1 Engineers 1 Spring

This preview shows document pages 1 - 8. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online