# Chapt 17 section 3 ```Voc Games
 http://www.quia.com/jg/1367083.html
Newton

The English
mathematician Sir Isaac
Newton restated
motion in the first of his
three laws of motion.
1st Law of Motion

Newton’s first law of
motion states that an
object at rest tends to
stay at rest and an
object in motion tends
to stay in motion with
the same speed and in
the same direction
unless acted upon by
an unbalanced force
Inertia
 Newton’s
first law is also called the law of
inertia. An object’s resistance to a change in
motion is called inertia.
 The amount of inertia an object has depends
on its mass.
 Objects with greater mass have more inertia,
and require a greater force to cause a change
in motion.
2nd Law of Motion
Newton’s second law
of motion states that
acceleration depends
on the object’s mass
and the net force
acting on the object.
 Acceleration = Net
Force
Mass

Acceleration
When acceleration is
measured in meters per
second per second
(m/s2)
 Mass is measured in
kilograms.
 Force is measured in
kilograms &times; meters per
second per second
(kg&middot;m/s2)

Newton
This unit is called the newton (N).
 One newton equals the force required to
accelerate one kilogram of mass at 1 meter
per second per second.
 1 N = 1 kg &times; 1 m/s2

Acceleration and Force
The acceleration of an object will increase if the
force increases.
 According to the equation, acceleration and force
change in the same way—both get larger.
 The equation also shows that the acceleration
will increase if the mass decreases.
 Acceleration and mass are inversely
proportional.

Math Practice (calculating net force)
1.
2.
3.
A speedboat pulls a 55kg water skier. The force
causes the skier to accelerate at 2.0m/s2.
Calculate the net force that causes this
acceleration
What is the net force on a 1000 kg object
accelerating at 3m/s2?
What net force is needed to accelerate a 25kg cart
at 14m/s2?
Think about what you are trying to
solve (net force)
 The
net force (Fnet)=
 A= Fnet
m
Fnet = (m)(a)