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Newtons laws of_motion

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rheann delostrino
rheann delostrino

Newton's three laws of motion are: 1) An object at rest stays at rest and an object in motion stays in motion unless acted upon by an unbalanced force. 2) The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object. 3) For every action, there is an equal and opposite reaction.

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NewtonsNewtons Laws ofLaws of MotionMotionI.I. Law of InertiaLaw of Inertia II.II. F=maF=ma III.III. Action-ReactionAction-Reaction
While most people knowWhile most people know what Newton's laws say,what Newton's laws say, many people do not knowmany people do not know what they mean (or simply dowhat they mean (or simply do not believe what they mean).not believe what they mean).
Newtons Laws of MotionNewtons Laws of Motion 11stst LawLaw An object at rest will stay at rest, An object at rest will stay at rest, and an object in motion will stay inand an object in motion will stay in motion at constant velocity, unless actedmotion at constant velocity, unless acted upon by an unbalanced force.upon by an unbalanced force. 22ndnd LawLaw Force equals mass timesForce equals mass times acceleration.acceleration. 33rdrd LawLaw For every action there is anFor every action there is an equal and opposite reaction.equal and opposite reaction.
11stst Law of MotionLaw of Motion (Law of Inertia)(Law of Inertia) An object at rest will stay atAn object at rest will stay at rest, and an object in motionrest, and an object in motion will stay in motion atwill stay in motion at constant velocity, unless actedconstant velocity, unless acted upon by an unbalanced force.upon by an unbalanced force.
11stst LawLaw Inertia is theInertia is the tendency of antendency of an object to resistobject to resist changes in itschanges in its velocity:velocity: whether inwhether in motion ormotion or motionless.motionless. These pumpkins will not move unless acted on by an unbalanced force.
11stst LawLaw Once airborne,Once airborne, unless acted onunless acted on by anby an unbalanced forceunbalanced force (gravity and air(gravity and air fluid friction), fluid friction), it would neverit would never stop!stop!
11stst LawLaw Unless actedUnless acted upon by anupon by an unbalancedunbalanced force, this golfforce, this golf ball would sit onball would sit on the tee forever.the tee forever.
Why then, do we observe everyWhy then, do we observe every day objects in motion slowingday objects in motion slowing down and becoming motionlessdown and becoming motionless seemingly without an outsideseemingly without an outside force?force? Its a force we sometimes cannot see Its a force we sometimes cannot see friction.friction.
Objects on earth, unlike theObjects on earth, unlike the frictionless space the moonfrictionless space the moon travels through, are under thetravels through, are under the influence of friction.influence of friction.
There are four main types of friction:There are four main types of friction: Sliding friction:Sliding friction: ice skating Rolling friction:Rolling friction: bowling Fluid friction (air or liquid):Fluid friction (air or liquid): air or water resistance Static friction:Static friction: initial friction when moving an object What is this unbalanced force that acts on an object in motion?What is this unbalanced force that acts on an object in motion?
際際滷 a book際際滷 a book across a table andacross a table and watch it slide to a restwatch it slide to a rest position. The bookposition. The book comes to a restcomes to a rest because of thebecause of the presencepresence of a force -of a force - that force being thethat force being the force of friction -force of friction - which brings the bookwhich brings the book to a rest position.to a rest position.
In the absence of a force of friction, the bookIn the absence of a force of friction, the book would continue in motion with the same speedwould continue in motion with the same speed and direction - forever! (Or at least to the endand direction - forever! (Or at least to the end of the table top.)of the table top.)
Newtonss 1Newtonss 1stst Law and YouLaw and You Dont let this be you. Wear seat belts.Dont let this be you. Wear seat belts. Because of inertia, objects (including you) resist changesBecause of inertia, objects (including you) resist changes in their motion. When the car going 80 km/hour is stoppedin their motion. When the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 m/hour.by the brick wall, your body keeps moving at 80 m/hour.
22ndnd LawLaw
22ndnd LawLaw The net force of an object isThe net force of an object is equal to the product of its massequal to the product of its mass and acceleration, or F=ma.and acceleration, or F=ma.
22ndnd LawLaw When mass is in kilograms and acceleration isWhen mass is in kilograms and acceleration is in m/s/s, the unit of force is in newtons (N).in m/s/s, the unit of force is in newtons (N). One newton is equal to the force required toOne newton is equal to the force required to accelerate one kilogram of mass at oneaccelerate one kilogram of mass at one meter/second/second.meter/second/second.
22ndnd Law (F = m x a)Law (F = m x a) How much force is needed to accelerate a 1400 kilogram car 2 meters per second/per second? Write the formulaWrite the formula F = m x a Fill in given numbers and unitsFill in given numbers and units F = 1400 kg x 2 meters per second/second Solve for the unknownSolve for the unknown 2800 kg-meters/second/second or 2800 N
If mass remains constant, doubling the acceleration, doubles the force. If force remains constant, doubling the mass, halves the acceleration.
Newtons 2nd Law proves that different masses accelerate to the earth at the same rate, but with different forces. We know that objects with different masses accelerate to the ground at the same rate. However, because of the 2nd Law we know that they dont hit the ground with the same force. F = maF = ma 98 N = 10 kg x 9.8 m/s/s98 N = 10 kg x 9.8 m/s/s F = maF = ma 9.8 N = 1 kg x 9.89.8 N = 1 kg x 9.8 m/s/sm/s/s
Newtons laws of_motion
Check Your UnderstandingCheck Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object?object? A 6 kg object? 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s22 .. Determine the mass.Determine the mass. 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec?3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.84. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?m/sec/sec?
Check Your UnderstandingCheck Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg object?1. What acceleration will result when a 12 N net force applied to a 3 kg object? 12 N = 3 kg x 4 m/s/s12 N = 3 kg x 4 m/s/s 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s22 . Determine the. Determine the mass.mass. 16 N = 3.2 kg x 5 m/s/s16 N = 3.2 kg x 5 m/s/s 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec?3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 66 kg-m/sec/sec or 66 N66 kg-m/sec/sec or 66 N 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 9800 kg-m/sec/sec or 9800 N9800 kg-m/sec/sec or 9800 N
Newtons laws of_motion
33rdrd LawLaw For every action, there is anFor every action, there is an equal and opposite reaction.equal and opposite reaction.
33rdrd LawLaw According to Newton,According to Newton, whenever objects A andwhenever objects A and B interact with eachB interact with each other, they exert forcesother, they exert forces upon each other. Whenupon each other. When you sit in your chair,you sit in your chair, your body exerts ayour body exerts a downward force on thedownward force on the chair and the chairchair and the chair exerts an upward forceexerts an upward force on your body.on your body.
33rdrd LawLaw There are two forcesThere are two forces resulting from thisresulting from this interaction - a force oninteraction - a force on the chair and a force onthe chair and a force on your body. These twoyour body. These two forces are calledforces are called actionaction andand reactionreaction forces.forces.
Newtons 3rd Law in NatureNewtons 3rd Law in Nature Consider the propulsion of aConsider the propulsion of a fish through the water. Afish through the water. A fish uses its fins to pushfish uses its fins to push water backwards. In turn,water backwards. In turn, the waterthe water reactsreacts by pushingby pushing the fish forwards, propellingthe fish forwards, propelling the fish through the water.the fish through the water. The size of the force on theThe size of the force on the water equals the size of thewater equals the size of the force on the fish; theforce on the fish; the direction of the force on thedirection of the force on the water (backwards) iswater (backwards) is opposite the direction of theopposite the direction of the force on the fish (forwards).force on the fish (forwards).
33rdrd LawLaw Flying gracefullyFlying gracefully through the air, birdsthrough the air, birds depend on Newtonsdepend on Newtons third law of motion. Asthird law of motion. As the birds push down onthe birds push down on the air with their wings,the air with their wings, the air pushes theirthe air pushes their wings up and giveswings up and gives them lift.them lift.
Consider the flying motion of birds. A bird flies byConsider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push airuse of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the birddownwards. In turn, the air reacts by pushing the bird upwards.upwards. The size of the force on the air equals the size of theThe size of the force on the air equals the size of the force on the bird; the direction of the force on the airforce on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on(downwards) is opposite the direction of the force on the bird (upwards).the bird (upwards). Action-reaction force pairs make it possible for birdsAction-reaction force pairs make it possible for birds to fly.to fly.
Newtons laws of_motion
Other examples of NewtonsOther examples of Newtons Third LawThird Law The baseball forces theThe baseball forces the bat to the left (anbat to the left (an action); the bat forcesaction); the bat forces the ball to the right (thethe ball to the right (the reaction).reaction).
33rdrd LawLaw Consider the motion ofConsider the motion of a car on the way toa car on the way to school. A car isschool. A car is equipped with wheelsequipped with wheels which spin backwards.which spin backwards. As the wheels spinAs the wheels spin backwards, they grip thebackwards, they grip the road and push the roadroad and push the road backwards.backwards.
33rdrd LawLaw The reaction of a rocket isThe reaction of a rocket is an application of the thirdan application of the third law of motion. Variouslaw of motion. Various fuels are burned in thefuels are burned in the engine, producing hotengine, producing hot gases.gases. The hot gases push againstThe hot gases push against the inside tube of the rocketthe inside tube of the rocket and escape out the bottomand escape out the bottom of the tube. As the gasesof the tube. As the gases move downward, the rocketmove downward, the rocket moves in the oppositemoves in the opposite direction.direction.

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Newtons laws of_motion

  • 1. NewtonsNewtons Laws ofLaws of MotionMotionI.I. Law of InertiaLaw of Inertia II.II. F=maF=ma III.III. Action-ReactionAction-Reaction
  • 2. While most people knowWhile most people know what Newton's laws say,what Newton's laws say, many people do not knowmany people do not know what they mean (or simply dowhat they mean (or simply do not believe what they mean).not believe what they mean).
  • 3. Newtons Laws of MotionNewtons Laws of Motion 11stst LawLaw An object at rest will stay at rest, An object at rest will stay at rest, and an object in motion will stay inand an object in motion will stay in motion at constant velocity, unless actedmotion at constant velocity, unless acted upon by an unbalanced force.upon by an unbalanced force. 22ndnd LawLaw Force equals mass timesForce equals mass times acceleration.acceleration. 33rdrd LawLaw For every action there is anFor every action there is an equal and opposite reaction.equal and opposite reaction.
  • 4. 11stst Law of MotionLaw of Motion (Law of Inertia)(Law of Inertia) An object at rest will stay atAn object at rest will stay at rest, and an object in motionrest, and an object in motion will stay in motion atwill stay in motion at constant velocity, unless actedconstant velocity, unless acted upon by an unbalanced force.upon by an unbalanced force.
  • 5. 11stst LawLaw Inertia is theInertia is the tendency of antendency of an object to resistobject to resist changes in itschanges in its velocity:velocity: whether inwhether in motion ormotion or motionless.motionless. These pumpkins will not move unless acted on by an unbalanced force.
  • 6. 11stst LawLaw Once airborne,Once airborne, unless acted onunless acted on by anby an unbalanced forceunbalanced force (gravity and air(gravity and air fluid friction), fluid friction), it would neverit would never stop!stop!
  • 7. 11stst LawLaw Unless actedUnless acted upon by anupon by an unbalancedunbalanced force, this golfforce, this golf ball would sit onball would sit on the tee forever.the tee forever.
  • 8. Why then, do we observe everyWhy then, do we observe every day objects in motion slowingday objects in motion slowing down and becoming motionlessdown and becoming motionless seemingly without an outsideseemingly without an outside force?force? Its a force we sometimes cannot see Its a force we sometimes cannot see friction.friction.
  • 9. Objects on earth, unlike theObjects on earth, unlike the frictionless space the moonfrictionless space the moon travels through, are under thetravels through, are under the influence of friction.influence of friction.
  • 10. There are four main types of friction:There are four main types of friction: Sliding friction:Sliding friction: ice skating Rolling friction:Rolling friction: bowling Fluid friction (air or liquid):Fluid friction (air or liquid): air or water resistance Static friction:Static friction: initial friction when moving an object What is this unbalanced force that acts on an object in motion?What is this unbalanced force that acts on an object in motion?
  • 11. 際際滷 a book際際滷 a book across a table andacross a table and watch it slide to a restwatch it slide to a rest position. The bookposition. The book comes to a restcomes to a rest because of thebecause of the presencepresence of a force -of a force - that force being thethat force being the force of friction -force of friction - which brings the bookwhich brings the book to a rest position.to a rest position.
  • 12. In the absence of a force of friction, the bookIn the absence of a force of friction, the book would continue in motion with the same speedwould continue in motion with the same speed and direction - forever! (Or at least to the endand direction - forever! (Or at least to the end of the table top.)of the table top.)
  • 13. Newtonss 1Newtonss 1stst Law and YouLaw and You Dont let this be you. Wear seat belts.Dont let this be you. Wear seat belts. Because of inertia, objects (including you) resist changesBecause of inertia, objects (including you) resist changes in their motion. When the car going 80 km/hour is stoppedin their motion. When the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 m/hour.by the brick wall, your body keeps moving at 80 m/hour.
  • 15. 22ndnd LawLaw The net force of an object isThe net force of an object is equal to the product of its massequal to the product of its mass and acceleration, or F=ma.and acceleration, or F=ma.
  • 16. 22ndnd LawLaw When mass is in kilograms and acceleration isWhen mass is in kilograms and acceleration is in m/s/s, the unit of force is in newtons (N).in m/s/s, the unit of force is in newtons (N). One newton is equal to the force required toOne newton is equal to the force required to accelerate one kilogram of mass at oneaccelerate one kilogram of mass at one meter/second/second.meter/second/second.
  • 17. 22ndnd Law (F = m x a)Law (F = m x a) How much force is needed to accelerate a 1400 kilogram car 2 meters per second/per second? Write the formulaWrite the formula F = m x a Fill in given numbers and unitsFill in given numbers and units F = 1400 kg x 2 meters per second/second Solve for the unknownSolve for the unknown 2800 kg-meters/second/second or 2800 N
  • 18. If mass remains constant, doubling the acceleration, doubles the force. If force remains constant, doubling the mass, halves the acceleration.
  • 19. Newtons 2nd Law proves that different masses accelerate to the earth at the same rate, but with different forces. We know that objects with different masses accelerate to the ground at the same rate. However, because of the 2nd Law we know that they dont hit the ground with the same force. F = maF = ma 98 N = 10 kg x 9.8 m/s/s98 N = 10 kg x 9.8 m/s/s F = maF = ma 9.8 N = 1 kg x 9.89.8 N = 1 kg x 9.8 m/s/sm/s/s
  • 21. Check Your UnderstandingCheck Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object?object? A 6 kg object? 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s22 .. Determine the mass.Determine the mass. 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec?3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.84. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?m/sec/sec?
  • 22. Check Your UnderstandingCheck Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg object?1. What acceleration will result when a 12 N net force applied to a 3 kg object? 12 N = 3 kg x 4 m/s/s12 N = 3 kg x 4 m/s/s 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s22 . Determine the. Determine the mass.mass. 16 N = 3.2 kg x 5 m/s/s16 N = 3.2 kg x 5 m/s/s 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec?3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 66 kg-m/sec/sec or 66 N66 kg-m/sec/sec or 66 N 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 9800 kg-m/sec/sec or 9800 N9800 kg-m/sec/sec or 9800 N
  • 24. 33rdrd LawLaw For every action, there is anFor every action, there is an equal and opposite reaction.equal and opposite reaction.
  • 25. 33rdrd LawLaw According to Newton,According to Newton, whenever objects A andwhenever objects A and B interact with eachB interact with each other, they exert forcesother, they exert forces upon each other. Whenupon each other. When you sit in your chair,you sit in your chair, your body exerts ayour body exerts a downward force on thedownward force on the chair and the chairchair and the chair exerts an upward forceexerts an upward force on your body.on your body.
  • 26. 33rdrd LawLaw There are two forcesThere are two forces resulting from thisresulting from this interaction - a force oninteraction - a force on the chair and a force onthe chair and a force on your body. These twoyour body. These two forces are calledforces are called actionaction andand reactionreaction forces.forces.
  • 27. Newtons 3rd Law in NatureNewtons 3rd Law in Nature Consider the propulsion of aConsider the propulsion of a fish through the water. Afish through the water. A fish uses its fins to pushfish uses its fins to push water backwards. In turn,water backwards. In turn, the waterthe water reactsreacts by pushingby pushing the fish forwards, propellingthe fish forwards, propelling the fish through the water.the fish through the water. The size of the force on theThe size of the force on the water equals the size of thewater equals the size of the force on the fish; theforce on the fish; the direction of the force on thedirection of the force on the water (backwards) iswater (backwards) is opposite the direction of theopposite the direction of the force on the fish (forwards).force on the fish (forwards).
  • 28. 33rdrd LawLaw Flying gracefullyFlying gracefully through the air, birdsthrough the air, birds depend on Newtonsdepend on Newtons third law of motion. Asthird law of motion. As the birds push down onthe birds push down on the air with their wings,the air with their wings, the air pushes theirthe air pushes their wings up and giveswings up and gives them lift.them lift.
  • 29. Consider the flying motion of birds. A bird flies byConsider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push airuse of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the birddownwards. In turn, the air reacts by pushing the bird upwards.upwards. The size of the force on the air equals the size of theThe size of the force on the air equals the size of the force on the bird; the direction of the force on the airforce on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on(downwards) is opposite the direction of the force on the bird (upwards).the bird (upwards). Action-reaction force pairs make it possible for birdsAction-reaction force pairs make it possible for birds to fly.to fly.
  • 31. Other examples of NewtonsOther examples of Newtons Third LawThird Law The baseball forces theThe baseball forces the bat to the left (anbat to the left (an action); the bat forcesaction); the bat forces the ball to the right (thethe ball to the right (the reaction).reaction).
  • 32. 33rdrd LawLaw Consider the motion ofConsider the motion of a car on the way toa car on the way to school. A car isschool. A car is equipped with wheelsequipped with wheels which spin backwards.which spin backwards. As the wheels spinAs the wheels spin backwards, they grip thebackwards, they grip the road and push the roadroad and push the road backwards.backwards.
  • 33. 33rdrd LawLaw The reaction of a rocket isThe reaction of a rocket is an application of the thirdan application of the third law of motion. Variouslaw of motion. Various fuels are burned in thefuels are burned in the engine, producing hotengine, producing hot gases.gases. The hot gases push againstThe hot gases push against the inside tube of the rocketthe inside tube of the rocket and escape out the bottomand escape out the bottom of the tube. As the gasesof the tube. As the gases move downward, the rocketmove downward, the rocket moves in the oppositemoves in the opposite direction.direction.