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Chapter 3 Forces

Section 1 Newton's 2nd Law. The acceleration of an object depends on its mass as well as the force exerted on it.Force, mass, and acceleration Example: Softball with mass of 0.20kg and baseball with mass of0.14kgSoftball has less velocity after it leaves your hand. Newton's 2nd Law of Motion. New

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Chapter 3 Forces

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    1. Chapter 3 Forces Mr. Robinson Science Instructor

    2. Section 1 Newton’s 2nd Law The acceleration of an object depends on its mass as well as the force exerted on it. Force, mass, and acceleration Example: Softball with mass of 0.20kg and baseball with mass of0.14kg Softball has less velocity after it leaves your hand

    3. Newton’s 2nd Law of Motion Newton’s 2nd law of motion describes how force, mass, and acceleration are connected The net force acting on an object causes the object to accelerate in the direction of the net force

    4. Motion Equation

    5. Newton’s 2nd Law The SI units, the unit of mass is kilogram (kg), and the unit of acceleration is meters per second squared (m/s2) Force has the units kg x m/s2 is called the Newton (N)

    6. Friction Friction is the force that opposes motion between two surfaces that are touching each other The amount of friction between two surfaces depends on two factors The kinds of surfaces The force pressing the surfaces together

    7. What causes friction All surfaces have dips and bumps Areas where the highest bumps come in to contact with each other Areas where the bumps stick together are called “microwelds” Microwelds are the source of friction

    8. Microwelds

    9. Sticking Together The stronger the force pushing the two surfaces is, the stronger these microwelds will be More surface bumps=more contact To break these microwelds and move one surface over the other, a force must be applied

    10. Static Friction A force that resists the effort to move something is called friction Static friction is the friction between two surfaces that are not moving past each other

    11. Static Friction

    12. Sliding Friction Sliding friction is the force that opposes the motion of two surfaces sliding past each other Sliding friction is caused by microwelds constantly breaking and then forming again as the box slides along the floor

    13. Rolling Friction The friction between a rolling object and the surface it rolls on

    14. Air Resistance Acts on objects on objects that fall through the air The force of air resistance is in the opposite direction to the force of gravity Air resistance affects anything that moves in earth’s atmosphere Air resistance is pushing down

    15. Air resistance

    16. Air Resistance The amount of air resistance on an object depends on the speed, size, and shape of the object If no air resistance is present, then a feather and a apple will fall at the same rate

    17. Terminal Velocity When the forces on the falling object are balanced and the object no longer accelerates When it falls with a constant speed called the terminal velocity

    18. Section 2 Gravity Anything that has mass is attracted by the force of gravity Law of Gravity-any two masses exert an attractive force on each other Attractive Force depends on two factors Mass of the two objects Distance between the objects

    19. Gravity

    20. Gravitational Acceleration The gravitational attraction of Earth causes all falling objects to have an acceleration of 9.8m/s2 Newton’s second law, the net force, mass, and acceleration are related according to the following formula F= ma F=m X 9.8m/s2

    21. Weight The gravitational force on an object is called the object’s weight Gravitational Force=mass x acceleration Weight=Newton (N)

    22. Weight and Mass Weight and mass are not the same Weight is a force Mass is a measure of the amount of matter an object contains Weight and mass are related

    23. Weight and Mass

    24. Weightlessness=Free Fall

    25. Horizontal and Vertical Motions Gravity exerts an unbalanced force on a projectile, changing the direction of its path from only moving forward to a forward and downward force

    27. Centripetal Force Centripetal Acceleration toward the center of a curved or circular path Centripetal means move toward the center For a ball to be accelerating toward the center, an unbalances force called centripetal force

    28. Centripetal Force When a car rounds a sharp curve on a highway, the centripetal force is the friction between the tires and the road surface If road is wet or icy tires lose their grip

    30. Projectile Motion Anything that’s thrown or shot through the air is called a projectile Projectiles follow a curved path due to Earth’s gravity Projectiles have horizontal and horizontal velocities

    31. Satellites A satellite is anything that moves around another body in a generally circular path called a orbit Earth and the other planets are satellites because they orbit the Sun The International Space Station orbits the Earth is called Artificial Satellite

    33. Section 3 The 3rd Law of Motion “For every action there is a equal and opposite reaction force” When a force is applied in nature, a reaction to it occurs Example: shooting a gun and the kick back of the gun

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