Friction force Definition and 235 Threads

Consider a 2D circular bowl with a point mass moving inside, as shown in the picture. Assume that the normal force N acting on the mass is already known and keeps the mass constrained to the curved surface of the bowl. I want to model Coulomb friction in this system so that, for example, if I...

Hi, I started this thread to address the solution of this problem. Problem A yo-yo of radii ##R_1=R## and ##R_2=\frac{7}{5}R## is acted upon by forces ##F## and ##\kappa F~~~(0<\kappa<\infty)## as shown in the figure on the right. The yo-yo rolls without slipping on the horizontal...

I approached the problem using the work done by force equation (W=F*d) In my understanding all potential energy would have been converted into kinetic energy (KE) by point P (no friciton) We know d= L ; W= Wf ; f = Ff height = (H+h) So the Energy at point P is entirely kinetic: Which translates...

The elastic force of the board,N=G_1+G_2=1000N. The kinetic friction f=μN=200N. The tension T=f=200N.

Is there some kind of rule when we are supposed to use Fn×mu compared to F×mu or mg×mu to calculate friction? Because I don't get the same answer when I use Fn×mu and F×mu. In magnitude the forces are the same but they are not same in directions. Why is it so? Here is the photo. Problem goes...

I don't understand how to solve these, and I don't understand how an horizontal force can affect the friction force if it's defined by μ*N, and the additional force affect neither of those. I also don't understand how there is a range of possible forces that F can be to make the system static...

The answer is (D), but I don't understand why. Option (A) is wrong because the work done = 0. Then, I divide the motion into 3 parts: 1) motion on snowy surface Since the sledge is being pulled horizontally (let assume to the right), there will be tension force T to the right and friction...

I have searched online for this and found that it's due to friction. But for a rolling tyre there is only static friction acting and static friction produces no heat. For heat to be produced the two surfaces in contact must slide over each other i.e. there needs to be kinetic friction. Perhaps...

Hi so with this question, I am really confused. Even from the start. Like it doesn't tell us where the force is acting on. From top of block, middle of block etc? And I know how to determine the direction of moment for something on a pivot, not in this scenario though. The answer is A. They did...

Summary:: What is the sliding resistance of an eccentrically loaded block on a flat surface? If a 1000kg block is placed on a flat surface (say coeff. of friction = 0.4), what force does it take to slide if it loaded eccentrically, i.e. at the far edge of the block? My thinking is there is...

F.B.D Of first block (I have shown only the horizontal Forces) f1(max) = μ (1kg)(g) = 0.5 * 10 = 5N F.B.D Of the second Block f2(max) = μ (3kg)(g) = 15N Now the string will become taut and the tension will start acting when f = t = 5N But for 0<f<5N there will be no motion between the 1 kg...

I get how to solve (a); my method involves finding the net torque about the man's hands and setting it to zero, which can be used to solve for the normal force acting on his feet and the normal force on his hands can be solved using Newton's first law. Then divide by 2 for each to get the normal...

-i had begun by finding the normal force =147 N -then found the force of friction=99.96 N -found the work of friction=-799.68 J after that I am unsure of where to go since I don't have a force applied

In my teacher’s notes, it said that when the applied force on an object equals the maximum static frictional force, the object begins to move at constant velocity. My question is if both the applied force and the frictional force cancel as they are equal in magnitude, what force accelerates the...

Hi, actually it's not my homework, I'm just practicing some academic problems after a long break but it seems that I should post this here anyway. Here's a scheme of the problem that I want to solve: The task is to calculate minimum force ##P## for the system to stay in equilibrium. And...

hello there, I am wondering if my attempt at a solution for this particular problem correct?? I mean I know that the blocks won't move and the total friction force is 38.95N (at least lesser than that, since that is the maximum static friction). I saw someone attempted the solution but it is...

no idea

Consider a block on a sheet of paper. If the sheet is pulled without sliding the block, who has done work on the block (since it has undergone a kinetic energy variation)? I can not see another force doing work other than the static frictional force on the block.

Homework Statement A 39,000 lb truck A and a 3968 lb sports car B collide at an intersection. At the moment of the collision, the truck and the sports car are traveling with speeds vA = 70 mph and vB = 30 mph. Assume that the entire intersection forms a horizontal surface. Letting the line of...

Homework Statement Assume that block A which has a mass of 30 kg is being pushed to the left with a force of 75 N along a frictionless surface. What is the friction force of block A on block B if the block B has a mass of 24 kg and is accelerating at 0.50 m/s2 to the right relative to the block...

Homework Statement Consider the equation for the friction force Ff = m FN. is it possible to express the friction force as a tensor? If so, what rank tensor is it, and what are the ranks of the tensor m and the normal force FN? Homework Equations Ff = mFNThe Attempt at a Solution [/B] So I...

Got a question for you mechanics enthusiasts out there. Here https://i.imgur.com/Px0Hakg.jpg from what I gather is a basic force diagram depicting a car accelerating along a straight road, Dr represents the driving force of the engine, Fr the friction acting on the tyres against the direction of...

Homework Statement Two blocks m1 and m2 are connected by a weightless rod are on a inclined plane of ∅=37° and μ =0.25 .What is the common acceleration and Tension of rod if m1 is 4 kg and m2 is 2 kg such that the 4kg block is the upper block. OPTIONS A =4m/2 T=0 B =2m/2 T=5N C =10m/2 T=10N D...

I heard that the average professional boxer's force of punch is between 500-750lb. If the coefficient of static friction of rubber (from shoes) to say concrete is at most 0.85 then why can boxers get hit (especially in the chest) without losing footing? Does it have something to do with the...

I created this example to see if i can explain how humans walk but I can't. If I'm correct, when we push the ground to move forward we apply a force with the opposite direction (backward). Let's name this force Fp (for push). Because of that force, a friction force is being applied to us with...

Homework Statement A speed of a body of mass 8 kg is 6 m/s in position A. By the time it gets to B, the speed is measured to be 12 m/s. What is the frictional force opposing the motion? The incline is 30 degrees, the height of the ramp is 12 meters. Position A is at the top of the ramp...

Homework Statement You gradually apply a force to a 10. kg wood block on a wood table. What will the applied force on the block be once it is moving? The coefficients of static and kinetic friction are 0.5 and 0.3, respectively. The acceleration due to gravity is 9.8 m/s2. Homework Equations...

Homework Statement A satellite of mass m_s orbits the Earth in a circular orbit of radius r_0. If the satellite orbits at the upper part of the atmosphere and the friction force f is constant, it would trace an spiral and fall to the earth. but if we suppouse that the friction force is small...

Homework Statement If you have an object say in a vertical pipe, which only has a gravitational force acting on it would the reaction forces only be friction forces? If this is the case how would you calculate the forces? would you calculate the friction force using the friction coefficient or...

Homework Statement A force F is applied horizontally to a block A of mass mA = 0.600 kg so that it slides on the floor with acceleration g/3. Block B of mass mB = 0.200 kg rests on top of A, but is kept in place by a cord which is tied to the wall at 45.0°. The coefficient of kinetic friction...

Please do excuse if certain terms are not the most technical ones as I am translating the problem from another language. Do feel free to kindly inform me of the more technical term that substitues the sloppy one I've used. (And do excuse the generally bad English overall :-)) 1. Homework...

Homework Statement 14.6 The coefficient of kinetic friction between the slider and the rod is μ, and the free length of the spring is ##L_0 = b##. Derive the expression for the work done by the friction force on the slider as it moves from A to B. Neglect the weight of the slider. Homework...

Homework Statement The question is as follows: A 50kg ice skater is gliding along the ice, heading due north at 4.0m/s. The ice has a small coefficient of static friction, to prevent the skater from slipping sideways, but kinetic friction =0. Suddenly, a wind from the northeast exerts a force...

A uniform beam of length L and mass m is inclined at an angle θ to the horizontal. Its upper end is connected to a wall by a rope, and its lower end rests on a rough, horizontal surface. The coefficient of static friction between the beam and surface is μs. Assume that the angle θ is such that...

Homework Statement Box Mass = 64.7 kg T1 = 22.5° T2 = 54.1° F = 2327.9 N μdynamic = 0.19 μstatic = 0.37 What is the force of friction acting on the box? Homework Equations FF= mu x FN The Attempt at a Solution 64.7 x 9.81 = 634.707 0.19 x 634.707 = 120.69 Computer is telling...

Homework Statement How does an applied force and a frictional force compare when moving at constant velocity? Homework EquationsThe Attempt at a Solution

Can anyone help with the following question, please? 1. A 60,000kg train is being pulled up a 1 percent grade (it rises 1m for each horizontal 100m). The friction force opposing the motion of the train is 4,000N. Initial speed of the train is 12 m/s. Through what horizontal distance will the...

Homework Statement There is a mass m1 on an incline (angle α), connected to a pulley with a string, and on the other side of the pulley, after another string, there is a mass m2. See picture if it's unclear, I'm not sure how to express the problem. Anyway the plane has a friction coefficient...

I have few (more or less) general questions: 1. I know that: "The coefficients of friction are nearly independent of the area of contact between the surfaces". I understand this, but I know from everyday life, when car tire tread is worn off, braking distance increases and maximum acceleration...

A 30-cm-diameter, 1.6 kg solid turntable rotates on a 1.4-cm-diameter, 450 g shaft at a constant 33 rpm. When you hit the stop switch, a brake pad presses against the shaft and brings the turntable to a halt in 15 seconds. How much friction force does the brake pad apply to the shaft? I am...

I'm studying boundary layers. I am confused by what I am reading in this book. The book says the friction force (F) per unit volume = $$\frac{dF}{dy}=\mu\frac{d^2U}{dy^2}$$ They say $$\frac{dU}{dy}=\frac{U_\infty}{\delta}$$ This makes sense to me, delta is the thickness in the y direction...

Homework Statement A 50kg object begins at rest on a surface with a static coef of friction at 0.6. If you push horizontally on the object with a force of 27N, how quickly will it move across the surface? Homework Equations The Attempt at a Solution[/B] This is from Trivium Praxis test prep...

Homework Statement A boat of mass 1000 kg is moving at 25 m/s. The friction force ##f## is proportional to the speed ##v## of the boat, ##f = 70v##. How many time will take for the boat to reduce its speed to 12.5 m/s? Homework Equations ##\vec{F_r} = m \vec{a_r}## The Attempt at a Solution...

Homework Statement The 1.0 kg block in the figure is tied to the wall with a rope. It sits on top of the 2.0 kg block. The lower block is pulled to the right with a tension force of 20 N. The coefficient of kinetic friction at both the lower and upper surfaces of the 2.0 kg block is μk = 0.300...

Is there any case example where the friction force DOESNOT oppose the motion, but rather PROVOKES the motion of some object? I wondered about this all day long :D

Homework Statement The two blocks ##(m=16 kg)## and ##(M=88 kg )## , are not attached to each other.The coefficient of static friction between the blocks is ##μ=0.33##, but the surface beneath the larger block is frictionless.What is the minimum magnitude of the horizontal...

Homework Statement Two blocks,in contact,slide down an inclined plane ##AC## of inclination ##30^°##,The coefficient of kinetic friction between the ##2.0 kg## block and the incline is ##μ_1=0.20## and that between the ##4.0kg## block and the incline is ##μ_2=0.30##. Find the...

Homework Statement A 1000 kg boat is traveling at 100km/h when its engine is shut off.The magnitude of the frictional force ## \vec f_k## between boat and the water is proportional to the speed v of the boat:##f_k=70v##,where v is in meters per second and ##f_k## is in Newtons.Find...