6.4. A force of 300 N is sufficient to keep a 100-kg wooden crate moving at constant velocity across a wooden floor. Whatis the coefficient of kinetic friction? Supplementary Problems6.1. Ships are often built on ways that slope down to a nearby body of water. Often a ship is launched before most of itsinterior and superstructure have been installed, and is completed when afloat. Is this done because the added weightwould caise the ship to slide down the ways prematurely?6.2 A box is being pushed across a flor. Can the frictional force on the bos ever exceed its own weight? Can the frictionalforce ever exceed the applied force?61. An 80-lb wooden crate rests on a horizontal wooden Boor. If the coefficient of static friction is 0.5, how mach forceis needed to set the crate in motion?64. A force of 300 Nis suflicient to keep a 100-kg wooden crate moving at constant velocity across a wooden floor. Whatis the coefficient of kinetie friction?6.5. A force of 1000Nis applied to a 12001-kg car. If the coetficient of rolling friction is a04, what is the car's acceleration6.6. The coefficients of static and kinetic friction for stone on wood are, respectively, 0.5 and 0.4. If a 150-kg stone statue ispushed with just enough force to starn it moving across a wooden floor and the same force continues to act afterward,find the statue's acceleration.6.7. A car whose brakes are locked skids to a stop 70 m from an initial velocity of 80 km/h. Find the coellicient of kineticfriction.68. A driver sees a horse on the mad and applies the hrakes so hard that they lock and the car skids to a stop in 24 m. Theroad is level, and the coefficient of kinetic friction between tires and road is 0.7. How fast was the car going when thebrakes were applied?6.9. A truck moving at 100 kmvh carries a steel girder that rests on its wooken floor. What is the minimum time in whichthe truck can come to a stop without the girder moving forward? The coefficiest of statie frietion hetween steel andwond is 05.CamScanner - iga is guialCHAP 61FRICTION736.10. A car with its brakes locked will remain stationary on an inclined plane of dry concrete when the plane is it an angleof less than 45 with the horizontal. What is the coefficient of static friction of rubber tires on dry concrete?6.11. A steel ramp is to be built for sliding blocks of ice from a refrigeration plant down to ground level. If a- 0.05, findthe angle with the horizontal at which the ice will slide at constant velocity.6.12 A hox slides down a plane 8 m long that is inclined at an amgle of 30 with the horizontal. If the box starts from restand = 0.25, find (a) the acceleration of the bon, (b) its velocity at the hottom of the plane, and (e) the time requiredfor it to reach the bottiom.613. If the box of Prob. 6.10 has a mass of 60 kg, how mach force is needed to move it up the plane (a) at constant vekocityand (b) with an acceleration of 2 mis?6.14. A skier stands on a 5 slope. If the coefficient of static friction is 0.1, does the skier start to slide down?

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Answered: 64. A force of 300 Nis suflicient to…

64. A force of 300 Nis suflicient to keep a 100-kg wooden crate moving at comtant velocity acnos awooden foor. What is the coeflicient of kinetic friction?

International Edition---engineering Mechanics: Statics, 4th Edition

4th Edition

ISBN:9781305501607

Author:Andrew Pytel And Jaan Kiusalaas

Publisher:Andrew Pytel And Jaan Kiusalaas

Chapter4: Coplanar Equilibrium Analysis

Section: Chapter Questions

Problem 4.10P: Draw the FBD of the entire frame, assuming that friction and the weights of the members are...

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