Kinetic friction Definition and 509 Threads

https://scontent-dft4-1.xx.fbcdn.net/v/t35.0-12/14796269_10210868496286479_1115393743_o.jpg?oh=0ccd692c60a1d0bab84d5fbaf7e6197b&oe=580A1894 In the figure, a 6-kg box is sliding up an incline that makes an angle of theta=30 degree (with respect to the horizontal). As it slides up the incline, a...

Homework Statement a 10 kg box is moving on a level floor. The coefficient of static friction between the box and floor is 0.3. What is the force of kinetic friction? Homework Equations fk = FN * μk The Attempt at a Solution I rearranged the formula so that everything was set equal to the...

Homework Statement "A rope is used to pull a ##\frac{357}{100}kg## block at constant speed ##\frac{203}{50}m## across a horizontal floor. The force on the block from the rope is ##\frac{768}{100}N## and directed ##15°## above the horizontal. What are (a) the work done by the rope's force, (b)...

In the tablecloth trick, if we pull the tablecloth with a great force, the objects on it will stay on the table. But, if we pull it gently, the objects on it will still get along with the cloth movement. I know that if the force exceeds the maximum value of static friction, the objects will...

Homework Statement Homework Equations F=m*a ΣF(n-direction)= m*a(n)= m*(v^2/ρ) ∑F(t-direction)= m*a(t)\ Ffriction= Fn*coefficient(of friction) The Attempt at a Solution So I tried solving this question and apperently it is way easier than I thought. So I thought the kinetic friction has a...

As we all know, for the most part, the kinetic friction force is, for the most part, constant. After moving my cup across my table, this thought crossed my mind. If I move my cup across the table with a constant speed, then the force I'm applying must be equal to the kinetic friction force...

Homework Statement Sam, whose mass is 75 kg, stands at the top of a 12-m-high, 100-m-long snow-covered slope. His skis have a coefficient of kinetic friction on snow of 0.07. If he uses his poles to get started, then glides down, what is his speed at the bottom? Homework Equations v =...

Lets say that there is a rectangular box on a horizontal surface, with no air resistance on it. If the applied force required to get the object moving is greater than the static friction, Fa>Us* Fn, then the object starts moving. However, the Static Friction is almost always greater than the...

I think this question is not important and rarely noticed, but I'm still curious XD kinetic coefficient of friction is used when the applied force of static friction coefficient is less than than the force that we give, or less than or equal to the force that we give? sry for my bad english

Homework Statement Homework Equations friction:[/B] f = μN incline angle: θ = arctan(1/10) summation of forces in y: N - mgcosθ = 0 summation of forces in x: -f - mgsinθ = ma (?) The Attempt at a Solution For this problem, I set the x-axis going up the incline and the y-axis normal to said...

1. Homework Statement m = 4.00 kg theta = 30 v = 1 m/s compression of the spring by the block , x = 0.3 m d = 5 m Homework Equations rule : Fk = μ k * N i must find Fk first to find μ k using conservation energy, [/B] The Attempt at a Solution First find N, N = m x g x cos theta N = 4 *...

Homework Statement A particle of mass M is released from rest on a rough inclined plane, which makes an angle of 30° with the horizontal. It is observed that the particle moves a distance of 3 m in 3 s. What is the particle’s acceleration? Draw a properly labelled free body diagram. Calculate...

Homework Statement You are trying to slide a sofa across a horizontal floor. The mass of the sofa is 200 kg, and you need to exert a force of 350 N to make it begin to move. a) Calculate the coefficient of static friction between the floor and sofa b) after it starts moving, the sofa reaches a...

Homework Statement I have solved the problem where one mass m1 is on a horizontal frictional table connected to a mass m2 which is hanging off the table by a string over a pulley (assuming pulley massless), assuming that m2 is greater than m1 there is a net acceleration causing the mass 2 to...

Does rolling friction depend on the surface area? In other words, the size of the object placed? If I had a block and sphere of the same mass. Without static and kinetic friction coming into play. Which would experience greater rolling friction if they were on the same incline and of the same...

Homework Statement A 15kg crate slides across the floor. The coefficient of kinetic friction between the crate and the floor is 0.28. How much horizontal force is needed to accelerate the crate at 3.0 m/s/s? Homework Equations F=ma? The Attempt at a Solution F=? m= 15 kg u= 0.28 a= 3.0...

A box weighing 87 lb is being pulled with a rope that exerts a force of 60. lb at an angle of 15 degrees with the horizontal. If the coefficient of kinetic friction is .35, what is the kinetic friction?

Can someone please explain me the direction of static friction? I know kinetic friction is always going against the motion of an object but for static friction it depends.

Homework Statement in the question you're having to solve for this. A force is applied at a angle of 30 degrees on a object that weighs 12kg that is also moving at a constant velocity. kinetic friction is equal to .70 i am confused on how to find the Force applied to achieve a constant...

Homework Statement An electric motor is used to pull a 125 kg box across a floor using a long cable. The tension in the cable is 350N and the box accelerates at 1.2m/s2 (forward) for 5.0s. The cable breaks and the box slows down and stops. Calculating the coefficient of kinetic force? Given...

Homework Statement This isn't a problem from a textbook or homework but just a general question. Say there's a car traveling in a circle and that the track has some coefficient of kinetic friction µ. What would make the car skid? Homework EquationsThe Attempt at a Solution I'm thinking that...

Homework Statement A horizontal force of 150 N is used to push a 50.0 kg packing crate a distance of 5.00 m on a rough horizontal surface. The acceleration of gravity is 9.81 m/s2 . If the crate moves with constant velocity, calculate: a) the work done by the force. Answer in units of J. b)...

Homework Statement A heavy sled is being pulled by two people as shown in the figure. The coefficient of static friction between the sled and the ground is μs = 0.579, and the kinetic friction coefficient is μk = 0.435. The combined mass of the sled and its load is m = 336 kg. The ropes are...

Homework Statement While traveling on the highway with your 1000kg car, at 115.2 km/h, where you’re ABS (automatic braking system) is disabled. This means braking is relying solely on the friction of your tires with the road when they stop spinning. A dear jumps into the road 50 meters in...

Homework Statement At the instant shown the block is moving down the slope with P= 49 N, β= 38°, θ= 33° and M= 33 kg.Homework Equations What is the acceleration of the block up the slope if the kinetic coefficient of friction is 0.5? The Attempt at a Solution So I split all the forces into...

Homework Statement A crate on a rough horizontal floor is being moved horizontally by a force applied at a 16 degree angle above the horizontal. This is the smallest force that will move the crate at constant speed. What is the coefficient of kinetic friction? A : .11B : .27 C ...

Homework Statement A tradesman sharpens a knife by pushing it against a grindstone with a given applied force. The grindstone is 28kg, 15 cm in radius, is originally going at 200 rpm but is slowed down to 180 rpm over 10 s by applying the knife. The coefficient of kinetic friction is 0.20...

Homework Statement This is a theoretical question from my homework. We did a lab in class where we were using motion to see how kinetic friction is affected by different variables. We found the acceleration of a sliding wooden block (sliding on another wooded block), and then used that...

Homework Statement Given a 2.0 kg mass at rest on a horizontal surface at point zero. For 30.0 m, a constant horizontal force of 6 N is applied to the mass. For the first 15 m, the surface is frictionless. For the second 15 m, there is friction between the surface and the mass. The 6 N force...

Homework Statement What is the force of friction on the elastic powered car as it rolls across a smooth surface? GIVENS Displacement= 16.25m, Change in time= 22.5s, G=9.8m/s, Mass= 1kg UNKNOWNS V1=?, A=? Ff=? Homework Equations F=MA, A=V/T, Change displacement=((V1+V2)/2)T) The Attempt at a...

Homework Statement Block M1 is on top of block M2 which is on top of a horizontal frictionless surface. A horizontal force, F, is applied to M1. The coefficient of static friction is us and the coefficient of kinetic friction isuk. Find, a) the maximum force that can be applied to M1, such...

Hi, I understand that the static coefficient of friction dictates how much force is required to initiate motion/slippage and kinetic(dynamic) coefficient of friction dictates how much force is required to maintain motion/slippage. So considering a clutch with a friction and drive plate, what is...

Homework Statement While moving in, a new homeowner is pushing a box across the floor at a constant velocity. The coefficient of kinetic friction between the box and the floor is 0.41. The pushing force is directed downward and an angle θ below the horizontal. When θ is greater than a...

Assume a car has a smart regenerative braking system that optionally locks up the wheels with the tires skidding or allows the wheels to rotate while skidding, using the torque from the rotating and skidding tires to generate power into some type of kinetic energy recovery system. Assume the...

Homework Statement The total force needed to drag a box at constant speed across a surface with coefficient of kinetic friction Uk is least when the force is applied at an angle theta such that a.sin(theta) = Uk. b.cos(theta) = Uk. c.tan(theta) = Uk. d.cot(theta) = Uk. e.sec(theta) = Uk...

Homework Statement A 2.0 kg block of wood slides over a horizontal surface and comes to rest in 2.5 s. If its initial velocity was 9.0 m/s, what is the coefficient of kinetic friction? Homework Equations rho=mv change in rho=F*change in t Force of friction = mu*Force normal Force normal=mg...

Homework Statement [/B] The block shown is pulled across the horizontal surface at a constant speed by the force shown. If M = 5.0 kg, F = 14 N and Theta= 35°, what is the coefficient of kinetic friction between the block and the horizontal surface? Homework Equations Fx = Fcos(theta) Ff = Fn...

Homework Statement Problem: A 10 kg box slides down a hill and has a constant velocity. The angle of the hill is 10° with respect to the horizontal. What is the coefficient of kinetic friction between the surface of the hill and the box? Homework Equations Fn = mg + ma ƒk = μk * Fn The Attempt...

Homework Statement I know incline is 16 degrees I know distance traveled is 2.85 meters I know Vf is 2.71 meters/second I calculated the meu static and got .287 Homework EquationsThe Attempt at a Solution Tried every thing so lost

An Object slides with a consistent velocity down an incline that has a 30 degree angle. I'm trying to find the kinetic friction and the ratio that the mechanical energy is lost on the way down. I think I have already calculated µ with F(friction)= µmgcos(θ)=mgsin(θ) out comes Tan(θ) = µ I...

Homework Statement See, I was collecting data for a lab, and now when I look it at, I'm being asked to find the kinetic friction force and the coefficient of friction. What I was given was: the mass of the block: .261 kg gravity: 9.81 m/s2 the acceleration: -7.3125 m/s2 And that's it. If it...

Homework Statement A skier is sliding down a 20o slope at constant speed, what is the kinetic friction coefficient? Homework Equations E = 1/2 mv2 W = Fd F = ma F = μN = μmg The Attempt at a Solution Attempted to use ma = μmgsin20, which crosses out the masses since mass was not given, but...

Two astronauts are trying to figure out the mass of Mercury and the mass of Neptune. The astronauts decide to hit a 142 g ball with a bat on each planet and see how far it goes. They know the radius of mercury is 2,440 km and the radius of Neptune is 24,622 km. On mercury one astronaut hits the...

Homework Statement A person attaches a spring to an cubic object that weighs 36kg and pulls this object along a table made of material X horizontally with a steady speed of 1.3m/s. The spring stretches a distance of 3.4cm. Find the ratio of the spring constant to the kinetic friction...

Homework Statement Just found this site ,looks really helpful , so i am doing some revision using past exam papers and have a few head scratches you guys maybe able to help with . A car of mass 1000 kg is traveling at a speed of 25 m/s when it applies its brakes suddenly. The car immediately...

Homework Statement So a car owner wants to change his current tires and rims to a wider set of tires and rims for increased handling ability. However, the owner does not want to lose any acceleration performance due to the increased friction of having wider tires. To combat this, the owner...

Three blocks are connected as shown in the uploaded picture. The strings and friction-less pulleys have negligible masses, and the coefficient of kinetic friction between the 2.0 kg block and the table is 0.17. What is the acceleration of the 2.0 kg block? Homework Equations ∑F = ma The...

Hi, I'm new here and I'm having trouble with a question. 1. Homework Statement A 20.0-kg curling stone is released at the hog line and moves 28.35 m [W] to sit on the button and score a point. If the coefficient of kinetic friction between the stone and the ice is 0.00200, what was the...

1. A magazine reports that a new type of plastic ski is even more water repellent and that, on a gentle 203-m slope in the Alps, a skier reduced his time from 61 to 42 s with the new skis. Assuming a 3.0 degree slope, compute the coefficient of kinetic friction for each case. I am having...

Homework Statement The record speed for grass skiing was set in 1985 by Klaus Spinka, of Austria. Suppose it took Spinka 6.60 s to reach his top speed after he started from rest down a slope with a 34.0° incline. If the coefficient of kinetic friction between the skis and the grass was 0.198...