Newton's First Law, also known as the Law of Inertia, states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. It explains that an object's resistance to changes in motion is proportional to its mass. The document defines key terms related to Newton's First Law such as force, friction, mass, weight, and inertia. It also provides sample review questions testing understanding of the concepts.

1. Newton’s First Law
(law of inertia)

2. Newton’s First Law
(law of inertia)
An object at rest will
continue to stay at rest
unless an outside force
acts on it and …

3. Newton’s First Law
(law of inertia)
an object in motion will
continue to stay in
motion at constant speed
in a straight line unless
an outside force
acts on it

4. Newton’s First Law
(law of inertia)
FORCE is a push or a
pull applied to an object
that will cause it to start
moving, stop moving or
change its speed or
direction

5. Newton’s First Law
(law of inertia)
FRICTION is the force
that acts in the opposite
direction of the motion of
the object

6. Newton’s First Law
(law of inertia)
MASS is the measure of the
amount of matter in an object
measured in grams (g)
or kilograms (kg)

7. Newton’s First Law
(law of inertia)
WEIGHT is a measure of the
force of gravity on the mass of
an object
measured in Newtons (N)

8. Newton’s First Law
(law of inertia)

9. Newton’s First Law
(law of inertia)
INERTIA is a property of an
object that describes how hard
it is to change the motion of
the object
more mass means more inertia

10. REVIEW QUESTIONS
1. What is the difference between mass
and weight?
3. Which has more mass, 12 g of feathers
or 12 g of lead?
5. When an astronaut is living on the
International Space Station, what
happens to his mass?

11. REVIEW QUESTIONS
1. What would the mass of a dog be if it
has a weight of 100N?
3. What would the weight of an apple be if
it has a mass of 1.5 kg?
5. What is a force?

12. REVIEW QUESTIONS
1. What is friction?
3. What causes friction on a moving object?