Static friction Definition and 507 Threads

been working on this for a long time, haven't got far, keep getting a negative mass! Homework Statement A 440 g block on a frictionless surface is attached to a rather limp spring of constant k = 8.7 N/m. A second block rests on the first, and the whole system executes simple harmonic...

Suppose the designated speed for the ramp is to be 13.2 m/s (29.5 mi/h) and the radius of the curve is 34 m. The coefficient of static friction between the tires and the road is 0.33. What maximum speed could a car negotiate the exit ramp without skidding? Vmax = square root of...

[SOLVED] Non conservative forces: work + coefficient of static friction hey guys, I've been having a little trouble with some parts of this problem, hope someone can point me in the right direction A 20[kg] sled starts up a 30 degrees incline with a speed of 2.4[m/s] the coefficient of...

Homework Statement A child with poor table manners is sliding his 243 g dinner plate back and forth in SHM with an amplitude of 0.109 m on a horizontal surface. At a point a distance 6.70×10−2 m away from equilibrium, the speed of the plate is 0.250 m/s. a) What is the period? b) What is the...

Homework Statement A 25kg chair initially at rest on a horizontal floor requires a 165N horizontal force to set it in motion. Once the chair is in motion, a 127N horizontal force keeps it moving at a constant velocity. a.) Find the coefficient of static friction between the chair and the...

[SOLVED] Force Problem A 4.0kg block is put on top of a 5.0 kg block. The coefficient of static friction between the two blocks is u = 0.23 . The assembly of blocks is placed on a horizontal, frictionless table. What is the magnitude of the maximum horizontal force F that can be applied to...

We did a lab in physics class to determine the coefficient of static and sliding friction. basically we used a spring scale to determine how many Newtons of force was required to just get a block moving and then to keep it moving. We needed to do several trial runs with a slow, fast, and faster...

I get that when a car moves forward, its tires are rotating backwards, but the static friction from the ground, as a reaction force to the force from the tires, prevents the tires from moving backwards (not sure on this). So does the static friction only prevent the tires from moving backwards...

[SOLVED] Kinetic and Static Friction I've done so many of these but for some reason can't figure this one out. Any help iwll be greatly appreiciated. Here is the problem: A book of mass M = 0.55 kg rests on a table where the coefficient of static friction μs = 0.48. What is the minimum...

Homework Statement A coin is placed on a record that is rotating at 33.3 rpm. If the coefficient of static friction between the coin and the record is 0.3, how far from the center of the record can the coin be placed without having it slip off? Homework Equations a=v^2/r The Attempt...

A 2.0kg box rests on a plank that is inclined at a angle of 65 degrees above the horizontal. The upper end of the box is attached to a spring with a force constant of 360 N/m. If the coefficient of the static friction between the box and the plank is 0.22, what is the maximum amount the spring...

A block of mass m is at rest on an inclined plane that makes an angle of 30º with the horizontal, as shown in the figure. Which of the following statements about the force of static friction is true? A) fs > mg D)fs = mg sin 30º B) fs > mg cos 30º E) None of these statements is true. C) fs...

I'm having trouble with this one problem, I've tried everything with my given notes, but the right answer isn't coming up: A block with a mass of 3.7 kg is placed at rest on a surface inclined at an angle of 52 degrees above the horizontal. The coefficient of static friction between the...

[SOLVED] !Max Static Friction ! Homework Statement Its #8-5 and it goes with the diagram below. I Can't seem to get the equations to work out. I know I need three in three unknowns, which I thought I found, but one causes this to fail. Can anyone see my error? I have done this twice so far...

Homework Statement 1) If I have a ball rolling upwards on an incline, why is the static friction pointing upwards as well (my book does not explain this)? 2) Also, when I deal with a static equilibrium problem, why is it sometimes that the normal force is not perpendicular to the surface? I...

1. Describe a situation where you were dealing with static friction that wasn't a maximum Im getting stuck on this question. Cause i can't think of a situation please some help would be appreciated

Hi ! Can anyone help me I need help ... Problem : ************************************************** ********************** 1- A coffee cup on the dashboard of a car slides forward on the dash when the driver decelerates from 40 km/h to rest in 3.5 s or less, but not if he decelerates in a...

[SOLVED] Circular motion, static friction Homework Statement Hey, this is more of a concept question than a homework question, but here goes: If a ball is spun fast enough to move around the inside of a vertical cylinder at a roughly constant velocity for a few seconds without spiraling down...

When an object, such as a wheel, rolls across a surface, static friction allows it to move. When taking into account rotational motion accompanied by translational motion across such a surface, what effect does static friction have on it other than allowing the object to move...

This is not necessarily a homework problem, but a sample problem of my book that I do not quite understand. A rock climber with mass m = 55 kg rests during a "chimney climb," pressing only with her shoulders and feet against the walls of a fissure of width w = 1.0 m. Her center of mass is a...

1. if a car is speeding off on a surface of asphault, no slipping tires, estimate static friction for a drag racer that covers the quarter mile in 6 seconds My attempt: I made a Free Body Diagram: Weight (W) down wards, Normal force (fn) upwards, and friction static friction to the...

Can anyone tell me the coefficients of static friction for these material combinations? Or does anyone know where I might be able to find them. human skin - steel human skin - aluminum human skin - wood Thanks

Sorry to bother with yet another question today, but I'm a little lost with this one. QUESTION A box with a mass of 25 kg is at rest on a ramp inclined at 45 degrees to the horizontal. The coefficients of friction between the box and the ramp are us=0.78 and uk=0.65. a) Determine the...

can static friction do work?

hi, i am taking this physics course through correspondance and don't have anyone to help me. i am supposed to do a lab on measuring coefficients of friction. purpose of the lab is to determine whether tread design affects the coefficient of static friction for running shoes. i am supposed to...

[SOLVED] Coefficient of Static Friction Problem Homework Statement A baseball player with mass m = 73 kg, sliding into second base, is retarded by a frictional force of magnitude 460 N. What is the coefficient of kinetic friction µk between the player and the ground? Homework Equations...

Question Can static friction do work? If no, explain why, if yes, give an example. Attempts What I am thinking is when the car do circular motion , it does not slip off the road because the road provides the static frictional force as the centripetal force. However, static friction...

I'm curious as to what does the limit of the magnitude of static friction depends on between any two objects.

Homework Statement The weight of the block in the drawing is 84.0 N. The coefficient of static friction between the block and the vertical wall is 0.520. (a) What minimum force is required to prevent the block from sliding down the wall? in Newtons (b) What minimum force is...

1. What is the maximum speed with which a 1050-kg car can round a turn of radius 77 m on a flat road if the coefficient of static friction between tires and road is 0.80? What does the static friction have to do with this problem? Is the centripetal force equal to this friction? WHy? 2. A...

Hey guys, i attempted this question and got an answer but I'm not sure if i did it right, since it seemed too simple too me. http://www.physics.ubc.ca/~mattison/Courses/Phys170/p170-ps6.pdf It is question #4 on the link, and what i did was use kinematics to find acceleration then simply...

An un-tethered block sits on a flatbed truck as it accelerates up an incline that makes an angle of 15° with respect to the horizontal. If the truck speeds up at a rate less than 2.50 m/s2, the block remains on the truck. If the truck speeds up at a rate equal to or greater than this value...

Homework Statement A block sits on an inclined plane, which is slowly being raised. The block remains motionless until the angle the plane makes with the horizontal is 23°. At this angle, the block begins to slide down the plane. What is the coefficient of static friction between the plane...

Homework Statement A coin is placed on a turntable that is rotating at 45.0 rpm. If the coefficient of static friction between the coin and the turntable is 0.1, how far from the center of the record can the coin be placed without having it slip off? ______ cm Homework Equations F =...

I need to determine the coefficient of static friction for the following set-up. M1 = 380.45g M2 = 74.7g This is what I know... u=F/mg What I can't figure out is how to factor in the horizontal and vertical weights. Can anyone help? Thanks!

I know that static friction happens only when the object doesn't move. And if the maximum static friction=applied horizontal force, the object still remains at rest. I have already posted a topic about friction yesterday. But there is a problem here: Two crates are stacked on top of each other...

I have some confusions between static friction and kinetic friction: When the static friction equals to applied force on an object, an object doesn't move and stays at rest I think. How about if the static friction is larger than the applied force? Will the object still stay at the rest, that...

Homework Statement When you take your 1100-kg car out for a spin, you go around a corner of radius 55m with a speed of 15m/s. Assuming your car doesn't skid, what is the force exerted on it by static friciton?Homework Equations f_{}c=ma_{}c f_{}c=mv^{}2/r \sumf=ma The Attempt at a Solution...

Kim has her coffee cup on her car's dash when she takes a corner with radius 4m and 20km/hr. What is the minimum coefficient of static friction which would aloow the coffee cup to stay there without slipping? this is what i did, but i think it is wrong MU= friction force/normal force=...

a 52 N backpack is laying on a table with a spring attached to one side of it where force is applied and the spring stretches. The backpack begins to slide when the spring (k= 150 N/m) stretches by 2.50 cm. What is the coefficient of static friction between the backpack and the table? i set...

To move a large crate across a rough floor, you push on it with a force at an angle of 21 degrees below the horizontal, as shown in the figure: http://img227.imageshack.us/img227/4950/walker67ac0.jpg Find the force necessary to start the crate moving, given that the mass of the crate is...

An 55.0-N crate of apples sits at rest on a ramp that runs from the ground to the bed of a truck. The ramp is inclined at 30.0° to the ground. I sketched the problem using a popular paint program. I seem to be having problems visualizing components of the normal force for some reason. I know...

A box of textbooks of mass 24.5 kg rests on a loading ramp that makes an angle alpha with the horizontal. The coefficient of kinetic friction is 0.270 and the coefficient of static friction is 0.330. As the angle alpha is increased, find the minimum angle at which the box starts to slip...

Homework Statement A wooden roof is sloped at a 44 deg angle. What is the minimum coefficent of static friction between the sole of a roofer's shoe and the roof if the roofer is not to slip? Homework Equations coefficient of static friciton = friction force / Normal force The...

Homework Statement The floor of a railroad flatcar is loaded with loose crates having a coefficient of static friction of 0.25 with the floor. If the train is initially moving at a speed of 48 km/h, in how short a distance can the train be stopped at constant acceleration without causing the...

On a level road with its brakes on, the shortest distance in which a car traveling with 83 km/hr can stop is 95 m. This shortest distance occurs when the driver uses anti-lock brakes which means that the car brakes without skidding. What is the coefficient of static friction between the...

This is mostly a theoretical question, I'm studying mechanics by myself so I have no teacher to ask this. Homework Statement The minimum force needed to move a stationary object is equal to the max static friction. However, I just encountered a question that included a sloped surface and...

1. A 13,500 N car traveling at 50.0 km/h rounds a curve of radious 2.00m x 10 ^ 2. Find the following: A. the centripetal acceleration of the car (.965 m/s[2]) B. The centripetal force (13,500 N) C C. The minimum coefficient of static friction between the tires and the road that will allow...

Homework Statement A car goes around a curved stretch of flat roadway of radius R = 104.5 m. The magnitudes of the horizontal and vertical components of force the car exerts on a securely seated passenger are, respectively, X = 236.0 N and Y = 572.0 N. This stretch of highway is a...

Homework Statement Part 1: Rounding a flat, unbanked curve, which has a radius (r), the coefficient of static friction between the car and the road is 0.5. Find the max speed you can take the curve without sliding. Radius (r) = 25 m I'll be using (Us) to denote the coefficient of static...