Temas Variados / Problemas Resueltos Fisica Libro E. Tippens
Problemas Resueltos Fisica Libro E. TippensTrabajos Documentales: Problemas Resueltos Fisica Libro E. Tippens
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Enviado por: Albert 17 marzo 2011
Palabras: 5397 | Páginas: 22
[pic]; Fc = 2630 N, No
10-10. An 8-lb object swings in horizontal circle with a speed of 95 ft/s. What is the radius of the path, if the centripetal force is 2000 lb?
[pic]; R = 1.13 ft
*10-11. Two 8-kg masses are attached to the end of a tin rod 400 mm long. The rod is supported in the middle and whirled in a circle. The rod can support a maximum tension of only 800 N. What is the maximum frequency of revolution? [ R = (400 mm/2) = 200 mm ]
[pic]; v = 4.47 m/s
[pic]; f = 3.56 rev/s
*10-12. A 500-g damp shirt rotates against the wall of a washer at 300 rpm. The diameter of the rotating drum is 70 cm. What is the magnitude and direction of the resultant force on the shirt? [ R = (70 cm/2) = 35 cm; f = 300 rpm(60 s/min) = 1800 rev/s ]
Fc = 2.24 x 107 N, toward the center
*10-13. A 70-kg runner rounds a track of radius 25 m at a speed of 8.8 m/s. What is the central force causing the runner to turn and what exerts the force?
[pic]; Fc = 217 N, friction
*10-14. In Olympic bobsled competition, a team takes a turn of radius 24 ft at a speed of 60 mi/h. What is the acceleration? How many g’s do passengers experience? (60 mi/h = 88 ft/s)
[pic]; ac = 323 ft/s2 or 10.1 g’s
Flat Curves and Banked Curves
10-15. On a rainy day the coefficient of static friction between tires and the roadway is only 0.4. What is the maximum speed at which a car can negotiate a turn of radius 80 m?
vc = 17.7 m/s or 63.8 km/h
10-16. A bus negotiates a turn of radius 400 ft while traveling at a speed of 60 mi/h. If slipping just begins at this speed, what is the coefficient of static friction between the tires and the road? (60 mi/h = 88 ft/s)
[pic]; (s = 0.605
10-17. Find the coefficient of static friction necessary to sustain motion at 20 m/s around a turn of radius 84 m.
[pic]; (s = 0.486
*10-18. A 20-kg child sits 3 m from the center of a rotating platform. If (s = 0.4, what is the max
imum number of revolutions per minute that can be achieved without slipping?
(Slipping occurs when the centripetal force equals the maximum force of static friction.)
f = 0.182 rev/s (60 s/min); f = 10.9 rpm
*10-19. A platform rotates freely at 100 rpm. If the coefficient of static friction is 0.5, how far from the center of the platform can a bolt be placed to without slipping?
f = 100 rev/min (1 min/60 s) = 1.67 rev/s; (s = 0.5; R = ?
[pic]; R = 21.1 cm
10-20. Find the required banking angle to negotiate the curve of Prob.10-15 without slipping.
[pic]; ( = 21.80
10-21. Find the required banking angle for Problem 10-16 to prevent slipping?
[pic]; ( = 31.20
10-22. The optimum banking angle for a curve of radius 20 m is found to be 280. For what speed was this angle designed?
[pic]; v = 10.3 m/s
*10-23. A curve in a road 9 m wide has a radius of 96 m. How much higher than the inside edge should the outside edge be ...
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