Work-kinetic energy theorem
W = ǻKE
W = net work
KE = kinetic energy
What is the soccer ball’s speed
immediately after being kicked?
Its mass is 0.42 kg.
W = F ·ǻx
W = (240 N) (0.20 m) = 48 J
W = ǻKE = 48 J
KE = ½ mv^2 = 48 J
v^2 = 2(48 J)/0.42 kg
v = 15 m/s
6.6 - Sample problem: work-kinetic energy theorem
We assume here that all the work done by the athletes goes to increasing the kinetic energy of the sled.Four bobsledders push their 235 kg
sled with a constant force, moving it
from rest to a speed of 10.0 m/s along
a flat, 50.0-meter-long icy track.
Ignoring friction and air resistance,
what force does the team exert on the
sled?
(^126) Copyright 2007 Kinetic Books Co. Chapter 06