Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post....
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Transcript of Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post....
![Page 1: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/1.jpg)
Newton’s LawsJune 5, 2012
![Page 2: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/2.jpg)
![Page 3: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/3.jpg)
Sample Problem 1A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius of 0.11 m with a mass of 0.27 kg. What is the tension in the rope? What force does the pole exert on the ball?
![Page 4: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/4.jpg)
Sample Problem 2Two blocks are held in place on a frictionless incline. The mB = 10 kg and mA = 12 kg. The incline is tilted at an angle of 37o to the horizontal. Determine the tension in each rope.
![Page 5: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/5.jpg)
FrictionFriction is a resistive force. Kinetic friction is resistive to motion and static friction resists motion in the first place.
In general, static friction is greater than kinetic friction
![Page 6: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/6.jpg)
Kinetic Friction
Will always point in a direction opposite to the direction of motion
Ff = µkFn
![Page 7: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/7.jpg)
Sample Problem 3
A box of mass 25 kg is pushed across a floor at a constant speed of 2 m/sec. What force is needed to push the box if there is a coefficient of friction of 0.2 between the box and the floor?
![Page 8: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/8.jpg)
Sample Problem 4The weight of the crate is 500 N and there is a coefficient of friction between the crate and the floor of 0.4. If the worker pulls with a 400 N force, what is the acceleration of the crate?
![Page 9: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/9.jpg)
Sample Problem 5
A pig slides down a chute inclined at 30o. If there is a coefficient of friction between pig and slide of 0.6, what is the acceleration of the pig down the slide?
![Page 10: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/10.jpg)
Static FrictionResists the desire of an object to move.
Range of possibilities though we will typically look at the maximum case.
![Page 11: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/11.jpg)
Static Friction
![Page 12: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/12.jpg)
Static FrictionHarder to predict which way it will go.
Ffs < µsFn
Typical cases are the limits where Ffs = µsFn
![Page 13: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/13.jpg)
Sample Problem 6A person on a stationary 125 N box with a force of 75 N at 30o below the horizontal. Determine the coefficient of static friction if the box just starts to move.
![Page 14: Newtons Laws June 5, 2012. Sample Problem 1 A tetherball leans against a smooth, frictionless post. The string is 1.4 m long and the ball has a radius.](https://reader035.fdocuments.in/reader035/viewer/2022070305/5514dbbc550346935c8b5396/html5/thumbnails/14.jpg)
Sample Problem 7If the coefficient of static friction between the box and the truck bed is 0.6, what is the greatest acceleration the truck can have without the box slipping?