Transcript Forces - jessbiology

Concept Presentation
Forces Acting on Objects
By:Sonu Bhutani
Specific Expectations
• C2.1 use appropriate terminology related to
forces, including, but not limited to: mass, time,
speed, velocity, acceleration, friction, gravity,
normal force, and free-body diagrams
• C2.2 conduct an inquiry that applies Newton’s
laws to analyze, in qualitative and quantitative
terms, the forces acting on an object, and use
free-body diagrams to determine the net force
and the acceleration of the object.
• C2.5 plan and conduct an inquiry to analyze the
effect of forces acting on objects in one
dimension, using vector diagrams, free-body
diagrams, and Newton’s laws.
Lesson Sequence
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•
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Forces and types of forces – Review
Balanced and Unbalanced forces
Free Body Diagram
Calculation of net force
Effect of forces
What students should already know…
• Concept of force
• Types of forces
• Introduction to Newton’s Laws of
Motion
Introduction to the topic
The concept of forces is fundamental for
solving static and dynamic problems. The
motion of a body will change only if an
external force is applied to it. If several
forces are acting on an object, vector sum of
all forces that is the net force on the object
might change an object’s state of motion.
Free body diagram represent all the forces
acting an object. The free body diagram
allows you to set up problem properly so
that you can correctly solve for unknowns
such as forces and acceleration.
Balanced and Unbalanced forces-Video
http://www.teachertube.com/viewVideo.php?video_id=58727
Through this video teacher reviews
concept of Balanced and Unbalanced
forces.
Demonstration: Introduction to Free Body Diagrams
Forces on a speeding fish
Upthrust
Friction
Thrust
Weight
Force diagrams
Force diagrams help us
understand forces.
The force is represented
by an arrow.
A force diagram for a falling object
just after it starts to fall.
Air resistance
The direction the arrow
points shows the
direction the force is
acting.
The size of the arrow
can be used to compare
the size of the forces.
Weight
Free Body Diagrams-Video
http://youtu.be/cErlwSUXwsg
This is an excellent video explaining
how to draw free body diagrams with
the help of different examples.
Sample cards – Group activity
Drawing free body diagrams
A block hangs at rest from
the ceiling by a piece of rope.
Consider the forces acting on
the block and draw free body
diagram.
A block slides across the
top of a table. Consider only
the forces acting upon the
block and draw free body
diagram.
Free Body Diagram - Animation
www.physicsclassroom.com/shwave/fbd.cfm
Through this animation, students can
practice their skills at constructing free
body diagrams.
Inquiry Based Learning: Computer Simulation
http://phet.colorado.edu/en/simulation/forces-and-motion
Through this simulation students will study
qualitatively, how an external force will affect
the speed and direction of an object’s motion
with help of free body diagrams.
Potential difficulties by students
Students’ may face problem in:
•
Drawing free body diagrams.
•
Calculating net force.
•
Explaining the effect of force with
the help of free body diagrams.
Suggestions to student difficulties
•
•
•
To develop deeper understanding how to
draw free body diagrams, first visual
aids are used and then group activity is
assigned.
To solve problems related calculation of
net force, problem solving approach is
used that helps in understanding the
procedure well.
Inquiry based learning is introduced that
may help students in explaining affect of
force using free body diagrams.
Assessment / Evaluation
Quiz – Force and types of forces (K/U)
Questioning during video – Balanced and
Unbalanced forces (C)
Demonstration Reflection – free body
diagram (C)
Group Activity Rating Scale – Drawing free
body diagram (K/U & C)
Lab simulation – Effect of forces (I/C)
Culminating task rubric for lab simulation
task sheet (I & C)
Rubric for worksheet (K/U, A and C)
Unit Test (K/U, A and C)
Accommodations for Special Needs and ELL
•Encouraging High achieving peers to assist
the Special needs/ELL students in one to
one settings.
•Using hand on instruction, audio visual
materials, games, pictures and flash cards.
•Providing these students with extra time,
computer options, assistive technology etc.
•Providing more enrichment sheets to these
students to practice.
•Using co-operative learning setting, role
play, field trips and games that may help to
see natural/contextualized language.
Appropriate Internet sites related to topic
•http://www.physicsclassroom.com/Class/
The Physics Classroom Tutorial is an online physics tutorial with multimedia
and shockwave studios.
•http://hyperphysics.phyastr.gsu.edu/hbase/hframe.html
HyperPhysics is an exploration environment for concepts in physics which
employs concept maps and other linking strategies to facilitate smooth
navigation.
•http://phet.colorado.edu/
This site contains interesting computer simulations helping students to
develop deeper understanding about concept.
•http://www.mrfizix.com/home/applicationnewto
nlaws.htm#_top
You can find answers to your most complex physics questions, and even
find ideas for lab experiments and projects.
Practical applications & societal implications
Knowledge of force is required:
In principles of launching satellites
and rockets.
In working of cranes
In designing of Golf clubs
In development of technologies such as
crumple zone, seat belts and air bags.
By mountain climbers as they use nylon
ropes.
By a driver as negotiating sharp turns.