2. Inertia: This is the tendency of an object to resist any
change in its motion. This means that a moving object
tends to remain in motion and an object that is not
moving tends to remain still.
3. Newton’s First Law of Motion: An object at rest will
remain at rest and an object in motion will remain in
motion, at a constant velocity (keeping the same speed and
direction), unless acted upon by an unbalanced force. This
is often called the law of inertia.
Example of Newton’s First Law:
If you are in a car that stops
suddenly, the force of inertia
keeps your body moving forward.
The unbalanced force of the
seatbelt makes you stop.
4. Inertia is related to mass: It is easier to change the
motion of an object with small mass and more difficult
to change the motion of an object with greater mass.
It is easier to pull a small child in a wagon than it is to
pull a large adult. The child has less mass so it requires
less force to get the wagon started and less force to get it
to stop.
5. Newton’s Second Law of Motion: The net force of an
object results from multiplying the mass of the object by
the acceleration.
(Heavier objects are harder to move than lighter ones)
Force = Mass x Acceleration or F = m a
Mass is measured in kg and acceleration in m/s2
,
so the unit for force is kg m/s2
. This unit is called
the Newton or N. 1N = 1kg x 1m/ s2
.
50 N
6. When you increase force, your acceleration increases.
When you increase mass, your acceleration decreases.
a = 25N = 12.5 m/s2
2kg
2kg
25N
2kg
35N
a = 35N = 17.5 m/s2
2kg
5kg
25N
a = 25N = 5m/s2
5kg
7. When you increase force, your acceleration increases.
When you increase mass, your acceleration decreases.
a = 25N = 12.5 m/s2
2kg
2kg
25N
2kg
35N
a = 35N = 17.5 m/s2
2kg
5kg
25N
a = 25N = 5m/s2
5kg
