A sail deflects the wind,
and the wind exerts a force on the sail
Forces are involved when we do practically anything, such as
shove a book aside, pull a wagon up the drive way, pick up the
dirty clothes off the bedroom floor, go sailing, stretch a rubber
band, climb stairs, stop a car at a traffic light, run a comb through
tangled hair, pull on a shoe, scoop mounds of dirt with a bulldozer,
be dragged by a leash attached to an overly eager dog, or blow the
white puffy seeds off a dandelion.
The most common unit of force to most of us is the pound. Pounds and
Newtons do not just refer to weight (the gravitational force on an object), but are units of force no matter
what its cause. One pound is equal to 4.45 Newtons. So a 100 lb
student also weighs 445 Newtons.
