DO NOW: BELL RINGER
BALANCED VS UNBALANCED FORCES
AGENDA• Bell Ringer
• PowerPoint with Cornell Notes
• Net Force
• Balanced Force
• Unbalanced Force
• Distance-Time Graphs
• 10 Minute Net Force Challenge
• Worksheet
• Exit Slip
FORCE RECAP
• A force is a push or pull.
• Force is measured in Newtons (N).
• There are contact and non-contact forces.
• Contact forces such as applied force, normal
force, friction and air resistance work through
direct contact.
• Non-contact forces such as gravity, magnetism,
and electrical force work at a distance.
• The universal law of gravitation states that all
objects have this force of attraction. Mass and
distance affect the force of gravity.
NET FORCE
• Add when the forces are working together.
• Subtract the bigger number minus the smaller
number when the forces are working against each
other.
The sum of the forces acting on an
object.
NET FORCE PRACTICEGroup Activity
5N
10N
8N 8N
4N
20N
Answer:
Answer:
Answer:
N
BALANCED FORCES: HAVE A
NET FORCE OF 0 N• If the forces acting on a still object are
balanced, the object doesn’t move.
• If the forces acting on a moving object
are balanced, the moving object will
not change speed or direction.
• Balanced forces have a net force of
zero.
Drag is a mechanical force. It is generated by the interaction and
contact of a solid body with a fluid (liquid or gas).
Drag is a Resistance
to motion through a
fluid
UNBALANCED FORCES: HAVE A NET FORCE GREATER THAN 0.
• One of the opposing forces is greater.
• The object accelerates. That means it
moves, or speeds up, in the direction of
the greater force.
THINK!• The heavier something is, the harder it will be to
move it. The less massive something is, the less force
you will need to move it.
I’d like to
see you
try…Pick on someone
your own size!
NET FORCE?
BALANCED OR UNBALANCED?
Can you name this force?
50 N40 N
Net Force = 10 N to the left
Drag is a mechanical force. It is generated by the interaction and
contact of a solid body with a fluid (liquid or gas).
CALCULATING NET FORCE5- 10 MINUTE CHALLENGE
PRACTICE QUESTIONS
A spacecraft orbiting Earth moves to an orbit that is half as
far from the center of Earth. How does the gravitational
force between the spacecraft and Earth change?
A The gravitational force decreases.
B The gravitational force remains unchanged.
C The gravitational force increases.
D The gravitational force has effect only at Earth’s surface.
Students will describe the relationship among distance,
mass, and gravitational force between any two objects.
What characteristics can you use to describe a
force?
A. The direction in which it acts and its strength
B. Only the direction in which it acts
C. Only its strength
D. Its speed and the direction in which it acts
Aito carried out an experiment to separate the components in a mixture. The steps Aito took are shown in the illustration below .
What forces did Aito depend
upon to separate the
components in this mixture?
A magnetic and electrical forces
B gravitational and electrical forces
C magnetic and gravitational forces
D balanced and unbalanced forces
Which of the following is true about mass and
weight?
F. Mass and weight are not related.
G. Mass is always the same, weight may
change.
H. Weight is always the same, mass
maychange.
I. Mass depends on gravity, weight does
not.
At baseball practice, Takahiro and Alfredo both picked up the same bat and neither would let go until one of them had it for himself. Takahiro pulled the bat with a force of 15 newtons (N), while Alfredo pulled with a force of 20 newtons(N). Why did Alfredo end up with the bat?
a. because the net force was 5 N in Alfredo’s direction.
b. because the net force was 20 N in Alfredo’s direction.
c. because the force was 5 N in Takahiro’s direction.
d. because the net force was 15 N in Takahiro’s direction.
Leanna decided to rearrange her
bedroom by moving her dresser to the
opposite wall. She tried pushing it, but
found that the dresser would not move.
What force was Leanne NOT able to
overcome?
A. electrical force
B. magnetic force
C. balanced force
D. frictional force
Multiple forces can act on the same
object at the same time. When will two
forces acting on the same object result in
an unbalanced force on that object?
A. when the two forces cancel each other
b. when the two forces produce a net
force of 0 N
c. when the two forces apply different
forces from opposite directions
d. when the two forces apply the same
amount of force from opposite directions
Becky asked her classmate Manuel to help
her move a table to the other side of the
classroom. Becky pushed the table with a
force of 20 newtons (N) and Manuel pulled
the table, from the opposite side, with a
force of 25 N. What was the net force
acting on the table?
A. 5 N
B. 20 N
C. 25 N
D. 45 N
What characteristics can you use to describe a force?
A. The direction in which it acts and its strength
B. Only the direction in which it acts
C. Only its strength
D. Its speed and the direction in which it acts
The diagrams below show smooth
blocks of wood being pushed across the
same surface. The mass of the block
and amount of force applied are
labeled in each diagram. In which
diagram would the block of wood have
the greatest acceleration?
Each figure below shows a force
measured in Newtons pushing on a
block. If there are no other forces
pushing on the block, in which case is
the acceleration of the block greatest?
EXIT SLIP
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