1. Motion & Forces Note-taking

2. The park is 3 km west of the school.
Analyze the position in the description. Label the distance, direction and reference point.
The park is 3 km west of the school.
reference point
distance
direction

3. Differentiate between the distance and displacement for an object that started at point A and traveled as shown to point B.
Distance: 24 units Displacement: 2 units

4. NGSSS Check How do you describe an object’s position?
You describe the object’s distance and direction from a reference point.

5. Characterize motion. Motion The process of changing position.
Description depends on a reference point.

6. Distinguish concepts related to speed.
The distance an object moves in a unit of time
Constant speed
An object moves the same distance over a given unit of time.
Changing speed
The distance an object covers increases or decreases over a given unit of time.
Average speed
Total distance traveled divided by the total time.

7. Differentiate speed from velocity.
The distance an object moves in a unit of time.
The speed and the direction of a moving object.

8. Identify two ways to change an object’s velocity.
Change in speed
Changes in
Velocity
Change in direction

9. Contrast velocity with acceleration.
The speed and direction of a moving object.
A measure of the change in velocity during a period of time.

10. Distinguish concepts related to speed.
Change in Velocity
Description
Positive acceleration
The action of speeding up
Negative acceleration
The action of slowing down
Changing direction
Change in velocity because of change of direction.

11. Analyze It Explain why, in a description of your motion for a whole day, your displacement is probably 0 m. Identify a reference point in your explanation.
Even though you might travel a long distance throughout the day, you started the day and ended the day at the same reference point, your bed.

12. Organize information about distance-time graphs.
Plotted line
shows how
much an object’s
position changes
during each time
interval
y-axis shows
distance an
object travels
from a
reference point
x-axis shows
time during
which the
object travels
Does not show
object’s actual
path

13. Plot data that you provide in the table onto a distance-time graph
Plot data that you provide in the table onto a distance-time graph. Label the axes.

14. Assess the meanings of lines on a distance-time graph.
Changing steepness:
means change in speed
Straight line:
means constant speed

15. Characterize speed-time graphs.
x-axis shows
time at which the
object travels
y-axis shows
the speed of an object

16. Assess the meanings of lines on a speed-time graph.
Horizontal at y = 0:
Object is at rest; not moving
Horizontal at y > 0:
Object is moving at a constant speed
Slopes upward from left to right:
Means the object is speeding up (positive acceleration) over time
Slopes downward from left to right:
Means the object is slowing down (negative acceleration) over time

17. NGSSS Check How can a graph show you if the motion of an object is constant?
An object moves with a constant speed if the line on the graph is straight.

18. Plot data that you provide in the table onto a speed-time graph
Plot data that you provide in the table onto a speed-time graph. Label the axes.

19. Organize information about force.
Force: a push or a pull
Contact
one object to another that
is touching it
Noncontact
one object can apply to another
without touching it

20. Model factors that affect the force of gravity
Model factors that affect the force of gravity. Draw circles to represent masses as described.

21. Paraphrase how factors that affect the force of gravity between two objects.
Distance and Gravity
Mass and Gravity
As the distance between two objects increases, the gravitational force between the objects decreases.
As the mass of one or both objects increases, the gravitational force between them increases.

22. Differentiate mass from weight.
Mass is the amount of matter in an object; weight is a measure of the gravitational force acting on the object’s mass.

23. NGSSS Check What are some examples of contact and noncontact forces you have experienced today.
Examples: you apply a contact force when sitting on a chair, walking or carrying your backpack. You experience a noncontact force via gravity.

24. Organize information about friction.
Acts in
opposite
direction of
an object’s
motion
Type of
force:
contact
Friction
Affects a
heavier
object more
than a
lighter
object
Resists the
sliding
motion
of two
objects that
are touching

25. Identify the frictional force between objects and air.
Air resistance.

26. NGSSS Check What is the law of gravity.
All objects are attracted to each other by a gravitational force.

27. Explain combined forces on an object.
Factor
Explanation
Net force
The sum of all forces acting on an object.
Balanced forces
The net force on an object is 0 N.
Unbalanced forces
The net force on an object is not 0 N.
Net force = 0
The object does not move.
Net force = 0
The object moves in the direction of the larger force.

28. NGSSS Check What can happen when forces combine?
When more than one force acts on an object, the forces combine and act as one force.

29. Sequence the effect of forces on velocity.
The force of a
train engine is
greater than the
force of friction
The train
speeds up.
Change in velocity,
or acceleration
A train track
exerts a sideway
force on the train’s
wheels.
The train
changes
direction.
Change in velocity,
or acceleration

30. Identify two examples of constant motion produced by balanced forces.
An object at rest.
An object moving at a constant velocity.

31. NGSSS Check How do balanced and unbalanced forces affect motion?
Balanced forces keep an object in constant motion. Unbalanced forces cause objects to change their motion.

32. Compare Newton’s first law of motion to the meaning of inertia.
If the net force acting on an
object is zero, the motion of
the object does not change.
Inertia:
The tendency of an object
to resist a change in its
motion.

33. Relate mass to acceleration and net force as described in Newton’s second law of motion.
The net
force acting
on an
object
increases
Its acceleration increases
as its mass
increases
An object’s
acceleration decreases

34. Express the equation described by Newton’s second law of motion.
a = f/m
force
acceleration
mass

35. Restate Newton’s third law of motion
For every action, there is an equal and opposite reaction.

36. Connect It Suppose the world no longer had friction
Connect It Suppose the world no longer had friction! Describe how this would affect three activities in your morning before school.
You would probably slip and fall as soon as you tried to get out of bed. When you brushed your teeth, they would not get clean. You wouldn’t need to brush your hair because the hairs on your head would all lied smoothly against one another and not get tangled up.