BERNARD OSOO

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BERNARD OSOO

• BEJAMIN FRANKLIN HIGH SCHOOL
• PHYSICAL SCIENCE LESSON PLAN
• TOPIC FORCES
• SUB TOPIC LAWS OF MOTION

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LESSON OBJECTIVES

• Identify the law that states that objects change
  their motion only when a net force is applied.
• Relate the first law of motion to important
  applications, such as seat belt safety issues.
• Calculate force, mass, and acceleration by using
  Newtons second law.

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NATIONAL SCIENCE EDUCATION STANDARDSPHYSICAL
SCIENCE CONTENT STANDARDSPS 4a Motion and Forces

• Objects change their motion only when a net force
  is applied. Laws of motion are used to calculate
  precisely the effects of forces on the motion of
  objects. The magnitude of the change in motion
  can be calculated using the relationship F ma,
  which is independent of the nature of the force.
• Whenever one object exerts force on another, a
  force equal in magnitude and opposite in
  direction is exerted on the first object.

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KWL

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OVERVIEW

• This lesson covers Newtons first and second
  laws of motion, including problem-solving with
  the second law.

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ASSESSING PRIOR KNOWLEDGE

• Define the following
• Force.
• Mass.
• Acceleration.
• Balanced and unbalanced forces.

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• Force An action exerted on a body in order to
  change the bodys state of rest or motion it has
  magnitude and direction.
• Mass A measure of the amount of matter in an
  object.
• Acceleration The rate at which velocity changes
  over time an object accelerates if its speed,
  direction, or both change.
• Balanced force When the forces applied on an
  object produce a net force of zero.

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• Unbalanced force When two opposite forces acting
  on the same object are unequal.
• A change in motion occurs in the direction of the
  greatest force.

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BACKGROUND

• When you kick a soccer ball, you are applying
  force to the ball. At the same time, the ball is
  also applying force to your foot.
• Soccer players also experience force in the form
  of collisions with other players.

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ACTIVITY(2 Minutes)

• Hold a textbook at an arms length in front of
  your shoulders. Move the book from left to right
  and back again,
• Repeat these actions with a piece of paper.
• What differences do you notice between the effort
  needed to change the direction of the paper and
  the effort needed to change the direction of the
  textbook?
• ____________________________
• Why would there be a difference?
• _____________________________

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ACTIVITY ANSWERS

• You feel the effects of inertia.
• Inertia is the tendency of an object to resist
  being moved or, if the object is moving, to
  resist a change in speed or direction until an
  outside force acts on the object.
• The paper requires much less effort to move than
  the textbook.
• This is because the textbook has a greater mass.

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LAWS OF MOTION

• Every motion observed or experienced is related
  to a force.
• Sir Isaac Newton described the relationship
  between motion and force in three laws that we
  now call Newtons laws of motion.
• Newtons laws apply to a wide range of motion

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• A caterpillar crawling.
• A person riding a bicycle.
• A rocket blasting off into space.

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NEWTONS FIRST LAW

• An object at rest remains at rest and an object
  in motion maintains its velocity unless it
  experiences an unbalanced force.

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EXAMPLES

• If you slide a book across a rough surface, such
  as carpet. It soon comes to rest.
• On a smooth surface, such as ice, the book will
  slide much farther before stopping.
• Because there is less frictional force between
  the ice and the book, the force must act over a
  longer time before the book comes to a stop.
• Without friction, the book would keep sliding
  forever.

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• In a moving car, you experience the effect
  described by Newtons first law. As the car
  stops, your body continues forward
• Seat belts and other safety features are
  designed to counteract this effect.

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NEWTONS SECOND LAW

• The unbalanced force acting on an object equals
  the objects mass times its acceleration.
• Force mass x acceleration
• F ma

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EXPLANATION

• Newtons first law describes what happens when
  the net force acting on an object is zero the
  object either remains at rest or continues moving
  at constant velocity
• Newtons second law describes the effect of an
  unbalanced force on the motion of an object

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FORCE IS MEASURED IN NEWTONS

• Newtons second law can be used to derive the SI
  unit of force, the newton (N).
• One newton is the force that can give a mass of 1
  Kg an acceleration of 1 m/s2
• 1 N 1 Kg x 1 m/s2

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MATH SKILLSSAMPLE PROBLEM

• Zookeepers lift a stretcher that holds a sedated
  lion. The total mass of the lion and stretcher is
  175 Kg, and the lions upward acceleration is
  0.657 m/s2. What is the unbalanced force
  necessary to produce this acceleration of the
  lion and the stretcher?

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SOLUTION

• List the given and the unknown values.
• Given mass, m 175 kg
• Acceleration, a 0.657 m/s2
• Unknown force, F ? N
• Write the equation for Newtons second law.
• Force mass x acceleration
• F ma
• Insert the known values into the equation, and
  solve.
• F 175 kg x 0.657 m/s2
• F 115 Kg x m/s2 115 N

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SUMMARY

• An object at rest remains at rest and an object
  in motion maintains a constant velocity unless it
  experiences an unbalanced force.
• (Newtons first law).
• Inertia is the property of matter that resists
  change in motion.
• The unbalanced force acting on an object equals
  the objects mass times its acceleration, or F
  ma.
• (Newtons second law).

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Questions ?

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CELL INJECTION

• Force Feedback Interface for Cell Injection
• Introduction
• Manual pronuclei injection and intracytoplasmic
  sperm injection (ICSI) requires long training and
  has low success rates primarily due to poor
  control over the injection force. Consequently,
  there is a need for quantification of forces
  during biological cell injection and for an
  automated cell injection system, which can
  provide force feedback to the operator improving
  the success rate of the injection task. Drexel
  University has developed a force feedback
  interface, which has the capability of measuring
  forces in the range of µN-mN and provide a haptic
  display of the cell injection forces. The force
  sensor has been integrated with the
  biomanipulation system to detect forces in real
  time. Experiments were performed on two different
  varieties of egg cells to demonstrate the success
  in measuring forces in the range in µN-mN .The
  experimental results indicate the cell puncturing
  forces were consistent and the operator was able
  to feel the cell injection forces .

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