Graphics Reference
In-Depth Information
direction in a straight line. Again, this is not what we generally experience. If we
kick a ball into the air, it travels in the direction of the force, but it also describes
an arc as it moves upward and then downward, back toward the ground, as
a result of the gravitational pull of the earth. We may also see the ball swerve
as it moves through the air, again due to other forces acting on it— perhaps
asymmetry in the ball itself, either in its shape or its surface. Swerving may
also be due to any spin we put on the ball. Spin creates differences in air
pressure on one side of the ball to the other, and this difference creates lift in
the direction in which there is more turbulence. The result is that a ball is seen
to swing through the air. Many athletes use this principle to great effect when
throwing, hitting, or kicking a ball toward a given target in order to deceive an
opponent as to the trajectory of the ball.
FIG 2.5
The greater a force applied
to an object, the further it will move.
Force is required to overcome the
inertia within an object. The more
mass an object has, the greater the
force needed to move it.
Newton's Second Law of Motion
The second law of motion states that the greater the force applied to an object,
the greater is the acceleration of that object, though this acceleration is also
determined by and proportional to the mass of the object.
