Friction force Definition and 236 Threads

Homework Statement The circular disk of 595-mm radius has a mass of 16 kg with centroidal radius of gyration = 500 mm and has a concentric circular groove of 220-mm radius cut into it. A steady force T is applied at an angle θ to a cord wrapped around the groove as shown. If T = 41 N, θ = 39°...

1. Problem statement, all variables and given/known data. A 25kg box of books is in the back of the truck. The truck-box system has frictional coefficients (static = 0.4, kinetic = 0.25). You get in the truck and begin to drive in a straight line. Under these conditions a) After reaching your...

Calculating friction force on a truck on an incline? Homework Statement A 4200kg truck is parked on a 20 degree slope. How big is the friction force on the truck? The coefficient of static friction between the tires and the road is 0.90.Homework Equations F=ma Ff=mu*m*a The Attempt at a...

My textbook says, "for an object rolling without slipping down an incline, the frictional force fs is less than or equal to its maximum value. fs < μsFn Why is that? What happen it's greater than?? When do we have static friction in rotational motion? (for rolling object) Then in an example...

As far as I know, friction force is equal to the product of the normal force and coefficient of friction, hence is independent of surface area. So why is it that race cars have wider tyres than conventional vehicles?

Homework Statement A body of mass m is moving through a bumpy road. the distance between each 2 bumps is 2h and the height of every bump is h. The body starts at velocity V0 and stops on top of the third bump. The friction coefficient is μ. Ignore the acceleration needed to change the direction...

Homework Statement In earlier days, horses pulled barges down canals in the manner show in the figure below. Suppose that the horse pulls on the rope with a force of 7900N at an angle of 18 to the direction of motion of the barge, which is headed straight along the canal. The mass of the...

how can you tell if the frictional force is great enough to keep a car turning a curb in circular motion based on the coefficient of friction and the normal force?

If we have a box with mass m placed on a horizontal tabletop. Then we push the box a distance of d. THe coefficient of kinetic friction between the box and tabletop is .35. When we're asked to find the external work done on the block-table system, it's not the work done by the friction...

Homework Statement A 8.00kg block of ice, released from rest at the top of a 1.04m--long frictionless ramp, slides downhill, reaching a speed of 2.76m/s at the bottom. What is the angle between the ramp and the horizontal? This I calculated as 21.9 degrees What would be the speed of the ice...

Homework Statement A rifle bullet with a mass of 15.5 g traveling toward the right at 262 m/s strikes a large bag of sand and penetrates it to a depth of 24.2 cm. Determine the magnitude and direction of the friction force (assumed constant) that acts on the bullet. Homework Equations F⃗...

Homework Statement An 8kg ball moves down a 12m high inclined plane with a speed of 6m/s. By the time it reaches the bottom, the speed is measured to be 12m/s. What is the frictional force opposing the motion? The inclined plane has an angle of 30 degrees with respect to the ground. Homework...

Homework Statement A 60-N block rests on a 35 degree inclined plane. Determine the normal force and find the friction force that keeps the block from sliding. Homework Equations The Attempt at a Solution Drew the free body diagram with each vector, not sure how to figure the...

Homework Statement A 1200kg car rounds a dry curve (μ= .6)with a radius of 67 m banked at an angle of 12°. If the car is traveling @ 95 km/hr (26.4 m/s), will a friction force be required? If so how much and in what direction? Homework Equations Fn = mg cos 12° ƩFn sin 12° = m (v^2/r)...

Hi! I'm struggling with this problem from my Mechanics book. It's actually an Engineering book, but this problem actually seems like an elementary Physics problem - if it's not, someone please move it to the appropriate forum. I tried my best to translate it clearly, but if it's ambiguous or...

Hi all, This is my first post here. I finally decided to sign up after using the site for many years. I am working on a project involving a syringe mechanism. I am using a stock 6ml syringe. I'm trying to calculate the static friction of the rubber seal. I have measured both the pull...

Good afternoon! 1. The Setup One block of Mass M2 is resting on top of a frictionless surface. Another block, M1, is resting on top of the of the first block. There does exist a coefficient between these two blocks, μ. 2. What happens to the bottom block when a force less than μN is...

I was reading that the friction force involved in circular motion was in the same direction as the centripetal force; but I thought that the frictional was suppose to act in the opposite direction of the intended motion, is this not true? Also, I am having a hard time figuring out how a car...

Homework Statement Find the work done by friction force as it slides down an inclined plane in terms of... m (Mass) x (Displacement) μ (Friction Coefficient) θ (Angle of the inclined plane) Homework Equations ƩFnormal = mgcos(θ) ƩFhorizontal = mgsin(θ) ƩFfriction = μFnormal -...

Basically we did a lab where you attach a pulley to the desk with a clamp and then have a friction block (three types: cork, plastic, and felt) attached to a string which is attached to a hanging mass. This basic setup is called an atwood's machine. The purpose of the lab was to identify the...

Homework Statement The surfer (70kg) is standing over a board which has an angle of 10º with the horizontal. A wave acelerates him to the right at 1.0m/s^2. There is a force that prevents the surfer from sliding over the board. Homework Equations Calculate that force. What's the...

Homework Statement A car weighing 3220 lbs rounds a curve a 200 ft radius banked at an angle of 30deg. Find the friction force acting on the tires when the car is traveling at 60mph. Coefficient of friction is 0.9. Homework Equations i rotated the axes such that y-axis is...

Homework Statement While sliding, the only force acting on the block in the horizontal direction is that of friction. From the mass of the block and its acceleration, you can find the frictional force and finally, the coefficient of kinetic friction. Okay, so we are sliding a steel block with...

Homework Statement A 200N block is on a 35 degree incline with a frictionless, massless pulley and a weight on the other side, Fw= 220. The system is in equilibrium. What are the magnitude and direction of the frictional force on the 200N block? Homework Equations and The Attempt at...

Homework Statement Block A slides on a frictionless ramp, as shown (in the attachment). At the instant, the block is moving up the ramp with speed V. Block B rests on top of A, and does not slip, due to friction between A and B. What is the direction of the friction force acting on B...

Homework Statement Im working on some typical "Ramp being pulled up an incline" questions and have trouble understanding something. An example question where it stats a box is being pulled up a ramp like the image below: Image: http://i43.tinypic.com/jb486q.jpg Now, first: In order...

In (the partial) solution, why does it consider the Tension,T, for finding the friction force between m1 and the surface? The tension is only affecting m1 in the horizontal direction. From where, the vertical component is apperaing?

Homework Statement A horizontal spring with spring constant 200 N/m is compressed 20 cm and used to launch a box across a rough horizontal surface. After traveling a distance it stops. What is the work done by friction force? Homework Equations W = F \cdot d KE_{spring} = \frac{1}{2}k \Delta...

Homework Statement The following questions are in regard to the situation where you press an apple crate against a wall so hard that the crate cannot slide down the wall. a) What is the direction of the static frictional force (fs) on the crate from the wall? b) What is the direction of...

In Figure 6-63, a block weighing 22 N is held at rest against a vertical wall by a horizontal force of magnitude 60 N. The coefficient of static friction between the wall and the block is 0.55, and the coefficient of kinetic friction between them is 0.38. In six experiments, a second force is...

A block of mass m1 = 4 kg is put on top of a block of mass m2 = 5 kg. To cause the top block to slip on the bottom one while the bottom one is held fixed, a horizontal force of at least 12N must be applied to the top block. The assembly of blocks is now placed on a horizontal, frictionless...

Homework Statement This problem is regarding Friction Force: Imagine a skateboard, low and with well-oiled bearings. What would happen if, standing over it at rest, you begin to walk along its length? The Attempt at a Solution There are 4 options. I chose this one: It would start moving in...

I just had a general question regarding Friction. With the following information, how could i calculate Friction Force to overcome(assuming it is on a horizontal plane and not moving): Mass, Weight, Normal Force, μ( Coef of Friction) say the mass was 100, weight was 980, Normal Force was 980...

Homework Statement im having problems with this question...a body weighing 51kg is pulled on a horrizontal plane with coefficient of friction 0.3. a force of 300N is applied at angle x ... find the angle x? Homework Equations The Attempt at a Solution the only solution i hav come...

My teacher in mechanics says that when we have a force pushing an object (moving at constant velocity) forward we also have a friction force that equals to the force that is pushing the object. So if we call the friction force for Fr and the pushing force for F, F=Fr. But in my mind, when we...

Homework Statement Homework Statement [/b] am i right? please help me .. thnx Homework Statement the blocks shown in the figure are connected by flexible, inextensible cords passing over frictionless pulleys. at A, the coefficient fiction is 0.30 while at B, it is 0.40. compute the...

Gear Clamp Design--Describe Friction Force I need to know how much frictional force is exerted on both sides of the collet (the piece in the middle of the image) when a force 'p' is applied by the cap nut. (See attachment) This is my first post here. Let me know if I'm being too vague. :)

Homework Statement A block of mass M=3.4 kg is dragged over a horizontal surface by a force F=20.0 N. The block is displaced a distance d=17.0 m, the friction force Ff is 3.3 N. What is the work done by the friction force? Homework Equations Ff=μkFn The Attempt at a Solution I...

Any object rotating on the axis does stop because of some kind of friction force. What happens if the same object rotates in the vacuum ? does the friction force applies to it ? or does it stop at any point in time ? or does it continue to rotate forever ? Thanks & Regards, Niral Soni

Homework Statement "A 0.15 kg apple falls from a branch 20 m above the ground. If it hits the ground with a speed of 17 m/s, what was the average friction force (due to air resistance) exerted on the apple?" Homework Equations At first, I thought I would use conservation of energy, PE = KE +...

Why does the friction force oppose only the rotational motion of the bottom of a wheel? Also, when a wheel is moving down a ramp, why is the friction force UP the ramp when the rotational motion of the bottom wheel is also up the ramp? What is "sliding"? I'm having a real hard time...

Homework Statement What is the value of the rolling friction force given 1)Fnet=0.24N (deceleration up the ramp) and 2)Fnet=0.21N (acceleration down the ramp)? Homework Equations Fnet = Fgravity - Ffriction (?) The Attempt at a Solution Somehow I need to combine these values to...

A 4.0 kg block is dragged over a rough horizontal surface by a constant force of 20 N. The speed of the block increases from 3.0 m/s to 5.0 m/s in a displacement of 5.0 m. What is the magnitude of the work done by the friction force during this displacement? My work was the following: Ei...

I'm analysing the forces on a vacuum roller brush in an effort to determine the power and rpm's that will be required of an electric motor to rotate the shaft. At anyone time there will be three contact points with the bristles to the carpet. Assuming we want the roller brush around 5000 RPM...

Find speed with friction force and no mass?? Homework Statement A ski starts from rest and slides down a 22 degree incline 75m long. If the coefficient of friction is 0.090, what is the ski's speed at the base of the incline? If the snow is level at the foot of the incline and has the same...

Homework Statement A crate is located in the center of a flatbed truck. The truck accelerates to the east and the crate moves with it, not sliding at all. What is the direction of the friction force exerted by the truck on the crate? a) it is to the west b) it is to the east c) No...

Homework Statement A car of mass 1164kg was traveling around a 288m radius corner at a speed of 10.8m/s. What was the magnitude of the fiction force required to maintain the vehicles path? Homework Equations F=ma I have no idea after that The Attempt at a Solution I found mg =...

Homework Statement A 4000 kg truck is parked on a 15 degree slope. what is its friction force? please show work, i'd like to understand how to do this problem *** my college professor doesn't really teach in class, well let me take that back. he teaches some things but leaves us...

Homework Statement A horizontal force of 200 n is required to cause a 15 kg block to slide up a 20degree incline with acceleration of 25 cm/s^2. Find the friction force on the block and the coefficient of friction. ANSWERS: Friction force = 134N Coefficient of Friction = 0.65 Homework...

Homework Statement A coin is off-center on a turntable which is spinning at a constant velocity. The coin is not slipping. From what I have gathered, the radial acceleration of the coin is caused by the force of static friction on the coin. There is no tangential acceleration. Homework...