Concept explainers
|| Friction in an elevator. You are riding in an elevator on the way to the 18th floor of your dormitory. The elevator is accelerating upward with a = 1.90 m/s2. Beside you is the box containing your new computer; the box and its contents have a total mass of 28.0 kg. While the elevator is accelerating upward, you push horizontally on the box to slide it at constant speed toward the elevator door. If the coefficient of kinetic friction between the box and the elevator floor is μk =0.32, what magnitude of force must you apply?
Want to see the full answer?
Check out a sample textbook solutionChapter 5 Solutions
College Physics (10th Edition)
Additional Science Textbook Solutions
Introduction to Electrodynamics
University Physics Volume 1
Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (4th Edition)
Sears And Zemansky's University Physics With Modern Physics
- Two blocks, each of mass m, are hung from the ceiling of an elevator as in Figure P4.33. The elevator has an upward acceleration a. The strings have negligible mass. (a) Find the tensions T1 and T2 in the upper and lower strings in terms of m, a, and g. (b) Compare the two tensions and determine which string would break first if a is made sufficiently large. (c) What are the tensions if the cable supporting the elevator breaks? Figure P4.33 Problems 33 and 34.arrow_forwardA crate of weight Fg is pushed by a force P on a horizontal floor as shown in Figure P4.83. The coefficient of static friction is s, and P is directed at angle below the horizontal. (a) Show that the minimum value of P that will move the crate is given by P=sFgsec1stan (b) Find the condition on in terms of , for which motion of the crate is impossible for any value of P. Figure P4.83arrow_forwardA 60-kg skydiver is falling at a constant speed near the surface of Earth. The magnitude of the force of air friction acting on the skydiver is approximately1. 0 N2. 6 N3. 60 N4. 600 Narrow_forward
- Figure P5.68 2. In Fig. P5.68 m, = 20.0 kg and a = 53.1°. The coefficient of kinetic friction between the block and the incline is Hg = 0.40. What must be the mass of the hanging block if it is to descend 12.0 m in the first 3.00 s after the system is released from rest? m2arrow_forwardA toboggan approaches a snowy hill moving at 10.7 m/s. The coefficients of static and kinetic friction between the snow and the toboggan are 0.48 and 0.34, respectively, and the hill slopes upward at 44.0 ∘ above the horizontal. a) Find the magnitude of the acceleration of the toboggan as it is going up the hill. a = ? What is the direction of the acceleration as the toboggan is going up the hill? Up the hill or down the hill? Find the magnitude of the acceleration of the toboggan after it has reached its highest point and is sliding down the hill. a = ?arrow_forwardWhen a crate with mass 25.0 kg is placed on a ramp that is inclined at an angle a below the horizontal, it slides down the ramp with an acceleration of 4.9 m/s2. The ramp is not frictionless. To increase the acceleration of the crate, a downward vertical force F vector is applied to the top of the crate. What must F be in order to increase the acceleration of the crate so that it is 9.8 m/s2? How does the value of F that you calculate compare to the weight of the crate?arrow_forward
- Problem 5: An elevator brimming with passengers has a mass of 1500 kg. art (a) The elevator accelerates upward (in the positive direction) from rest at a rate of 1.5 m/s² for 2.5 s. Calculate the tension in the cable supporting the elevator in newtons. T-1.695 x 10¹ T-1470 x 10 ✔Correct! The elevator continues upward at constant velocity for 8.6 s. What is the tension in the cable, in newtons, during this time? ✔Correct! The elevator experiences a negative acceleration at a rate of 0.65 m/s² for 2.7 s. What is the tension in the cable, in newtons, during this period of negative acceleration? T-13725 7-1.373x10 ✔Correct! Part (d) How far, in meters, has the elevator moved above its original starting point? y 13725arrow_forwardYou bring a bathroom scale onto an elevator and press "up". Your mass is 65 kg. If the bathroom scale reads 750 N, (a) what is the acceleration of the elevator? You then press down and the acceleration downward is of the same magnitude. (b) While accelerating downward, you hold a small mass of 100 g attached to a string. What is the tension in the string? This elevator is in the new BU Data Science building where g = 10 m/s². Your work should include free body diagramsarrow_forwardYou are pulling a 100-kg crate along the floor. The coefficient of static friction between the crate and the floor is 0.55, and the coefficient of kinetic friction is 0.45. If you want the crate to accelerate at 2.4 m/s², what must be the magnitude of your horizontal force? O230 N O 120 N O 170 N O 60 N O 680 Narrow_forward
- A 500 kg piano is being lowered into position by a crane while two people steady it with ropes pulling to the sides. Bob’s rope pulls to the left, 15 degrees below horizontal with 500N of tension. Ellen’s rope pulls toward the right, 25 degrees below horizontal. a) What tension must Ellen maintain in her rope to keep the piano descending vertically at constant speed? b) What is the tension in the vertical main cable supporting the piano?arrow_forwardPlease write the solution clearlyarrow_forwardA sled and rider have a total mass of 61.0 kg. They are on a snowy hill. The coefficient of kinetic friction between the sled and the snow is 0.155. The angle of the hill's slope measured upward from the horizontal is 21.0°. What is the acceleration of the rider? |m/s² Is the acceleration greater, less than, or equal to your result if a more massive rider uses the same sled on the same hill? Explain. O Greater than: the acceleration scales according to the mass of the rider. O Greater than: the acceleration scales according to the ratio of the masses of the rider and sled. O Less than: the acceleration scales according to the ratio of the masses of the rider and sled. O Equal to: the acceleration is independent of mass. O Equal to: the acceleration scales according to the mass of the sled.arrow_forward
- Principles of Physics: A Calculus-Based TextPhysicsISBN:9781133104261Author:Raymond A. Serway, John W. JewettPublisher:Cengage LearningCollege PhysicsPhysicsISBN:9781285737027Author:Raymond A. Serway, Chris VuillePublisher:Cengage LearningPhysics for Scientists and Engineers: Foundations...PhysicsISBN:9781133939146Author:Katz, Debora M.Publisher:Cengage Learning