b) A 30.0kg crate is at rest on a floor as shown. The coefficient of static friction between the crate and floor is 0.450 and the coefficient of kinetic friction is 0.350. Calculate the minimum horizontal force (F) required to make the crate start sliding. F

b) A 30.0kg crate is at rest on a floor as shown. The coefficient of static friction between the crate and floor is 0.450 and the coefficient of kinetic friction is 0.350. Calculate the minimum horizontal force (F) required to make the crate start sliding. F

Principles of Physics: A Calculus-Based Text

5th Edition

ISBN:9781133104261

Author:Raymond A. Serway, John W. Jewett

Publisher:Raymond A. Serway, John W. Jewett

Chapter5: More Applications Of Newton’s Laws

Section: Chapter Questions

Problem 5P

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Similar questions

(a) Calculate the tension in a vertical strand of spider web if a spider of mass 2.00105kg hangs motionless on it. (b) Calculate the tension in a horizontal strand of spider web if the same spider sits motionless in the middle of it much like the tightrope walker in Figure 5.26. The strand sags at an angle of 12 below the horizontal. Compare this with the tension in the vertical strand (find their ratio).
(a) What is the maximum frictional force in the knee joint of a person who supports 66.0 kg of her mass on that knee? (b) During strenuous exercise, it is possible to exert forces to the joints that are easily 10 times greater than the weight being supported. What is the maximum force of friction under such conditions? The frictional forces in joints are relatively small in all circumstances except when the joints deteriorate, such as from injury or arthritis. Increased frictional forces can cause further damage and pam.
A block of mass 3.00 kg is pushed up against a wall by a force P that makes an angle of = 50.0 with the horizontal as shown in Figure P5.12. The coefficient of static friction between the block and the wall is 0.250. (a) Determine the possible values for the magnitude of P that allow the block to remain stationary. (b) Describe what happens if P has a larger value and what happens if it is smaller. (c) Repeat parts (a) and (b), assuming the force makes an angle of = 13.0 with the horizontal. Figure P5.12
A 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 P4.83
Suppose you have a 120-kg wooden crate resting on a wood floor, with coefficient of static friction 0.500 between these wood surfaces. (a) What maximum force can you exert horizontally on the crate without moving it? (b) If you continue to exert this force once the crate starts to slip, what will its acceleration then be? The coefficient of sliding friction is known to be 0.300 for this situation.
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The person in Figure P5.6 weighs 170 lb. As seen from the front, each light crutch makes an angle of 22.0 with the vertical. Half of the persons weight is supported by the crutches. The other half is supported by the vertical forces of the ground on the persons feet. Assuming that the person is moving with constant velocity and the force exerted by the ground on the crutches acts along the crutches, determine (a) the smallest possible coefficient of friction between crutches and ground and (b) the magnitude of the compression force in each crutch. Figure P5.6
In Example 4.6, we investigated the apparent weight of a fish in an elevator. Now consider a 72.0-kg man standing on a spring scale in an elevator. Starting from rest, the elevator ascends, attaining its maximum speed of 1.20 m/s in 0.800 s. It travels with this constant speed for the next 5.00 s. The elevator then undergoes a uniform acceleration in the negative y direction for 1.50 s and comes to rest. What does the spring scale register (a) before the elevator starts to move, (b) during the first 0.800 s, (c) while the elevator is traveling at constant speed, and (d) during the time interval it is slowing down?
The manager of a department store is pushing horizontally with a force of magnitude 200 N on a box of shirts. The box is sliding across the horizontal floor with a forward acceleration. Nothing else touches the box. What must be true about the magnitude of the force of kinetic friction acting on the box (choose one)? (a) It is greater than 200 N. (b) It is less than 200 N. (c) It is equal to 200 N. (d) None of those statements is necessarily true.
An object of mass m is dropped al t = 0 from the roof of a building of height h. While the object is falling, a wind blowing parallel to the face of the building exerts a constant horizontal force F on the object. (a) At what time t does the object strike the ground? Express t in terms of g and h. (b) Find an expression in terms of m and F for the acceleration ax of the object in the horizontal direction (taken as the positive x direction). (c) How far is the object displaced horizontally before hitting the ground? Answer in terms of m, g, F, and h. (d) Find the magnitude of the objects acceleration while it is falling, using the variables F, m, and g.
An automobile driver traveling down an 8% grade slams on his brakes and skids 30 m before hitting a parked car. A lawyer hires an expert who measures the coefficient of kinetic friction between the tires and road to be k = 0.45. Is the lawyer correct to accuse the driver of exceeding the 25-MPH speed limit? Explain.
(a) What is the maximum frictional force in the knee joint of a person who supports 66.0 kg of her mass on that knee? (b) During strenuous exercise it is possible to exert forces to the joints that are easily ten times greater than the weight being supported. What is the maximum force of friction under such conditions? The frictional forces in joints are relatively small in all circumstances except when the joints deteriorate, such as from injury or arthritis. Increased frictional forces can cause further damage and pain.