Kinetic Energy

Wnet = Fnet s

Wnet = (m a) s

a = ( vf - vi ) / t

s = vavg t = (1/2) ( vi + vf ) t

Wnet = m a s = m [ ( vf - vi ) / t ][ (1/2) ( vi + vf ) t ]

Wnet = (1/2) m ( vf - vi ) ( vi + vf )

Wnet = (1/2) m ( vf2 - vi 2 )

Wnet = (1/2) m vf2 - (1/2) m vi 2

KE = K = (1/2) m v 2
Varying Force

Work-Energy Theorem
Return to ToC, Ch7, Work and Energy

(c) Doug Davis, 2001; all rights reserved