Newtons laws of motion_VBEI
- 1. Vidya Bharti EducationalVidya Bharti Educational InstitutionsInstitutions
- 3. Newton’s Laws of MotionNewton’s 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 forceupon by an unbalanced force.. 22ndnd LawLaw – Force equals mass times– Force equals mass times acceleration.acceleration. 33rdrd LawLaw – For every action there is an– For 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 forceupon by an unbalanced force..
- 5. 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 unbalanced force that acts on an object in motion?What is unbalanced force that acts on an object in motion?
- 6. ExampleExample -Slide a book-Slide 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.
- 7. 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.)
- 8. Newtons’s 1Newtons’s 1stst Law and YouLaw and You Don’t let this be you. Wear seat belts.Don’t 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.in their motion.
- 10. 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, orand acceleration, or F=ma.F=ma.
- 11. 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.
- 12. 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
- 13. If mass remains constant, doubling the acceleration, doubles the force. If force remains constant, doubling the mass, halves the acceleration.
- 14. Newton’s 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 don’t 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
- 15. 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?
- 16. 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
- 18. 33rdrd LawLaw For every action, there is anFor every action, there is an equal and opposite reaction.equal and opposite reaction.
- 19. 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.
- 20. 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.
- 21. 33rdrd LawLaw Example :Consider theExample :Consider the motion of a car on themotion of a car on the way to school. A car isway to school. 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.
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