PHYS 211, Section 3 (Honors) – Review
Chapter 7: Kinetic Energy and Work
Kinetic energy: For a particle of mass m moving at speed v, the kinetic energy is
K = mv2.
Work: For a force F acting on an object at a point that moves from x1 to x2,
W = F · dx = Fd cos ,
where the last expression is valid when the force is constant during the displacement and the
displacement is along a straight line.
Work and kinetic energy: The net work done by all forces acting on an object equals the change in its
kinetic energy,
Wnet = K.
Power: Power P = dW/dt is the rate at which work is being done, or energy transferred between two parts
of a system; The power exerted by a force F acting on an object moving with velocity v is P = F · v.
Gravity: The work done by gravity over a displacement d at an angle with respect to the downward
vertical direction is
Wg = mgd cos , or –mg y.
Spring: The force exerted by a spring is given by Hooke's law,
Fspring = –kx.
The work done by a spring over a displacement from xi to xf is Wspring = kxi
2 – kxf
2.
website by luca bombelli <bombelli"at"olemiss.edu>; content of this page last modified on 7 oct 2009
