A Friction Experiment During an experiment, a crate is pulled along a rough horizontal surface by a force F⃗ and the magnitude of the acceleration along the x direction, ax , is measured.(Figure 1) The vector F⃗ has a component along the x direction of magnitude Fx . The experiment is repeated several times, with different values of Fx each time, while maintaining a constant value for, Fy , the vertical component of F⃗ . |
Part A Create a plot of the force of static friction, fs , versus the x component of the pulling force, Fx , for the experiment. Let the point Fmin , along the horizontal axis, represent the minimum force required to accelerate the crate. Choose the graph that most accurately depicts the relationship among fs , Fx , and Fmin . (Figure 2) Please ChooseA B C D E SubmitHintsMy AnswersGive UpReview Part Part B Create a plot of the force of kinetic friction, fk , versus the x component of the pulling force, Fx , for the experiment. Let the point Fmin , along the horizontal axis, represent the minimum force required to accelerate the crate. Choose the graph that most accurately depicts the relationship among fk , Fx , and Fmin . (Figure 3) Please ChooseA B C D SubmitHintsMy AnswersGive UpReview Part Part C After all the trials are completed, a graph of acceleration ax as a function of force Fx is plotted. Assuming the presence of both static and kinetic friction, which of the following graphs (Figure 4) is most nearly correct? Please ChooseA B C D SubmitHintsMy AnswersGive UpReview Part Provide FeedbackContinue |
||
Figure 1Figure 2Figure 3Figure 4 of 4
|
The concept required to solve this question is frictional forces and Newton’s second law of motion.
The static friction is the frictional force that comes from interlocking of the irregularities of the two surfaces in contact and prevents any relative motion some limit occurs, where the motion starts. For the lower applied forces the static friction matches the applied force until the threshold of the motion.
Kinetic friction occurs the two rough surfaces are moving with respect to each other. Once the motion starts, frictional resistance decreases and it is approximately constant for some range of speeds.
The relationship between minimum force required to start the motion is related to normal reaction N by following relation:
Here, is the coefficient of static friction.
The kinetic friction is given as the product of coefficient of kinetic friction and normal reaction N.
The relation between applied force and acceleration by balancing the forces according to the Newton’s second law of motion is given as follow:
(A)
The plot between static friction and pulling force in x- direction is given below:
From this plot, both static friction and applied force along the interface is proportional to each other and a point comes when static friction becomes zero.
(B)
The plot between kinetic friction and pulling force in x- direction is given below:
In this plot, the kinetic friction is zero for the force less than and attains a constant value after the motion starts.
(C)
The plot between acceleration and pulling force in x- direction is given below:
In this plot, the acceleration is zero for the force less than and increases with increase in force after that.
Ans: Part AThe graph D is correct, as in it the frictional force is balanced by static friction up to .
A Friction Experiment During an experiment, a crate is pulled along a rough horizontal surface by a force F⃗ a...
Pulling Two Blocks In the situation shown in the figure, a person is pulling with a constant, nonzero force F⃗ on string 1, which is attached to block A. Block A is also attached to block B via string 2, as shown. For this problem, assume that neither string stretches and that friction is negligible. Both blocks have finite (nonzero) mass. (Figure 1) Part A Which one of the following statements correctly descibes the relationship between the accelerations of blocks...
A 50.0-kg crate is being pulled along a horizontal, smooth surface The pulling force is 10.0 N and is directed 20.0" above the horizontal What is the acceleration of the crate? An object of mass 25 kg, attached to an ideal massless spring, is pulled across a frictionless surface. If the spring constant is 100 N/m and the spring is stretched by 0.5 m, calculate the acceleration of the object when released.
A 1,440-N crate is being pushed across a level floor at a constant speed by a force of 250 N at an angle of 20.0° below the horizontal;(a) What is the coefficient of kinetic friction between the crate and the floor?(b) If the 250-N force is instead pulling the block at an angle of 20.0° above the horizontal, as shown in the figure (b), what will be the acceleration of the crate? Assume that the coefficient of friction is the...
You push a crate of mass M along a rough horizontal surface from point A to point C. The figure shows a top view. The absolute value of the work done by friction A B O is independent of the path. O depends on the speed of the crate. O is greatest along path A-C. O is greatest along path A-B-C.
A 40 kg crate is pulled 50 m along a horizontal floor by a constant force exerted by a person, Fp = 150 N, which acts as 30 degree angle. The floor is rough and exerts a friction for Ff = 40 N. Determine: a) the work done by each force acting on the crate b) the net work done on the crate
A block is pulled along a rough horizontal surface by force of magnitude 100 Newtons, at an angle of 30 degrees as shown. The block has a mass M=20.0 kg, and the coefficient of kinetic friction between the block and the surface is 0.50. a)The horizontal component of the tension, T, is b)The normal force exerted upward by the floor on the block has a magnitude of c)If the block moves 10.0 m to the right, the work done by...
1) It is friction that provides the force for a car to accelerate, so for high-performance cars the factor that limits acceleration isn't the engine; it's the tires. Part A For typical rubber-on-concrete friction, what is the shortest time in which a car could accelerate from 0 to 70 mph? Suppose that ?s=1.00, ?k=0.80, and ?r=0.02. 2.) The forces in (Figure 1) are acting on a 1.0 kg object. What is ax, the x-component of the object's acceleration? 3.)A crate...
Tactics Box 5.1 Working with Friction ForcesLearning Goal:To practice Tactics Box 5.1 Working with friction forces.Although friction is a complicated force, many aspects of it can be described with a simple model. This Tactics Box presents the conditions under which these models are valid and outlines the essential steps in solving friction problems.TACTICS BOX 5.1 Working with friction forces1. If the object is not moving relative to the surface it's in contact with, the friction force is static friction. Draw...
Three identical blocks connected by ideal strings are being pulled along a horizontal frictionless surface by a horizontal force F⃗ . (Figure 1) The magnitude of the tension in the string between blocks B and C is T = 3.00 N . Assume that each block has mass m = 0.400 kg .What is the magnitude F of the force?What is the tension TAB in the string between block A and block B?
Learning Goal: To be able to interpret potential energy diagrams and predict the corresponding motion of a particle. Potential energy diagrams for a particle are useful in predicting the motion of that particle. These diagrams allow one to determine the direction of the force acting on the particle at any point, the points of stable and unstable equilibrium, the particle's kinetic energy, etc. Consider the potential energy diagram shown. (Figure 1) The curve represents the value of potential energy U...