Friction Definition and 998 Threads

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 You are driving with your car (of total mass: 1.2tonnes) with a speed of v=50km/h, until you see an obstacle. a) What is the kinetic energy of the car? b) When you start to brake, there is still 15m until the obstacle. What must be the size of the friction coefficient (µ)...

This may be one of those things that everybody knew but me (come to think of it, I think I'll add it to the "things I learned today" thread elsewhere). There are some plastic bags I use which come on a roll. I have been struggling to open them when I remove a bag from the roll, rubbing...

Homework Statement The question says "A block of mass 4kg on a friction less inclined plane at angle of 30° is connected by a cord over massless friction less pulley to a second block of mass 2.3kg hanging vertically. What is the magnitude of acceleration of each block." Given m1 = 4 kg m2 =...

Hi Everyone, I am working on a project which involves building an extremely low friction turntable. To give you an idea of how low, we're placing a tank full of water on top of the turntable, placing a stirrer into the tank, turning the stirrer on and trying to get the tank to rotate on the...

Homework Statement We shot a projectile with mass ##m## and velocity ##v_0## with angle ##\phi## it collide with a box with mass ##M## at the maximum height of its path. Then, they both start to move with another speed. (We define ##t=0## at this time) (Completely Inelastic Collision). The box...

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...

Homework Statement We have a cart (It is very long) and a box on it.They are at first stationary but at ##t=0##, cart begins to move with ##v## such that: ##v = \alpha t^\beta ; t\leq t_0## and ##\dot v = c; t>t_0 ## where ##\alpha ,\beta ,c## are constants. At the time ##t1 (t_1<t_0)## the...

Homework Statement There is a train of length d and speed v. It is heading towards a hill with height h and length of each side l. What velocity requirement must be met so that the train can go up and down the hill? Homework Equations Ek=m⋅v2/2 Ep=m⋅g⋅h The Attempt at a Solution I'm basically...

Can anyone please explain to me how can I calculate the "Tension" and "acceleration" of M in this question interms of M,m1,m2 and g? I can't understand how M has an acceleration or why M is involved in the calculation of the tension my solution was that acc of M is zero and Tension = m1g x...

Hi, I just started learning physics at university and so I'm looking for help on a simple energy conservation problem. On the bottom right-hand of the image I attached below, you should see that it asks whether the initial speed would increase or decrease if the object was of a greater mass...

Homework Statement Block A is on top of Block B, both are of equal mass and size. Block B is being pulled by a hook at a constant velocity. There is friction between the table and block B. Homework Equations [/B] What will each FBD look like? Is there friction between Block A and Block B...

Homework Statement : A sled starts from rest at the top of a snow-covered incline that makes a 20° angle with the horizontal. After sliding 68 m down the slope, its speed is 17 m/s. Use the work–energy theorem to calculate the coefficient of kinetic friction between the runners of the sled and...

Homework Statement How would the motion of the block look like when the Force of kinetic friciton is more than the Limiting value of static friction? Homework Equations Kinteic Friciton=μN The Attempt at a Solution I think the block after overcoming the limiting value of static friction will...

Homework Statement A UTA Trax train engine can apply 96050 Newtons and locomotive has a mass of 1750 kg. The passenger car has a mass of 949 kg. (A) If the train accelerates at a rate of 1.29 m/s/s, how much friction is present in the passenger car? (Assume the locomotive moves...

Homework Statement A metal block of mass 10 kg is dragged on a rough horizontal surface with a constant speed of 5 m/s. If the coefficient of kinetic friction between the block and the road is 0.4, then the rate of generation of heat is. take g=10 m/s^2? Homework Equations F=ma Frictional...

Homework Statement So in physics we have this lab. Its simple, I'm just bad at physics...so bare with me. The objective of the lab is find the coefficient of friction (on a flat surface not on inclined planes and such not sure if this makes a difference (I should know if it does but I don't and...

Homework Statement The coefficient of kinetic friction between the block of mass m1 = 2.5 kg and the plane in Fig. 6 below is 1/6. Find (a) the acceleration of the block and (b) the tension in the string. Take g = 10 m/s2. Homework Equations Fnet=ma The Attempt at a Solution please i don't...

Homework Statement The question is similar to last week’s, except that we will consider how friction may damp the oscillation with time. A block with mass m shown in the drawing is acted on by a spring with spring constant k. The block is pulled distance [x[/0] from equilibrium position (x=0)...

Homework Statement A man pushes a 50 kg box up a 20-degree ramp at constant velocity. If the pushing force is parallel to the ramp, and the coefficient of friction is 0.4, how much force is he pushing with? Homework Equations u=Fs, max/Fn Not sure if this equation is needed. The Attempt at a...

Homework Statement [/B] 2. Homework Equations Fs = Nμ W = mg Fy = Fsin(θ) Fx = Fcos(θ) The Attempt at a Solution [/B] Hello all at PhysicsForums, I have a question on angled force and static friction. From my attempt below, I think I have found the maximum force required and would need...

Homework Statement The maximum power output of a car of mass 500kg is 75kW. Up a hill of angle 11.534, its maximum (constant) speed achievable with this power is 30m/s. What is the energy dissipated by frictional forces every second, and what must the frictional force be? Homework Equations...

Homework Statement Two blocks of masses m1 and m2 are placed on a table in contact with each other as shown in the figure below. The coefficient of kinetic friction between the block of mass m1 and the table is μ1, and that between the block of mass m2 and the table is μ2. A horizontal force of...

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...

If i have two blocks on top of each other and there is friction between the two blocks and it's a kinetic friction ( given μk). if i was given the force applied on the lower block to the right direction for example. ignoring the friction between the lower block and the ground, i tried to draw...

Homework Statement a mass m1 is attached to a second mass m2 by an acme (massless, unstretchable) string. m1 sits on a table with which it has coefficients of static and dynamic friction μs and μk respectively. m2 is hanging over the ends of a table, suspended by the taut string from an acme...

Homework Statement In the figure above a block of mass m is connected to a block of mass M > m by a string. Both blocks sit on a smooth surface with a coefficient of kinetic friction µk between either block and the surface. In figure a), a force of magnitude F (large enough to cause both blocks...

Homework Statement A 2.5 kg block is initially at rest on a horizontal surface. A horizontal force of magnitude 5.8 N and a vertical force are then applied to the block. The coefficients of friction for the block and surface are μs = 0.43 and μk = 0.24. (a) Determine the magnitude of the...

Homework Statement A truck (mass M) is carrying a box (mass m) in its flatbed, traveling along a straight, level road at speed v, when the driver sees a deer in the road a distance d ahead. The driver slams on the brakes to cause the truck to skid to a stop. The coefficient of kinetic friction...

Homework Statement A large box of mass M is moving on a horizontal surface at speed v_0. A small box of mass m sits on top of the large box. The coefficients of static and kinetic friction between the two boxes are μs and μk, respectively. Find an expression for the shortest distance dmin in...

Homework Statement A 10kg crate is placed on a horizontal conveyor belt. Draw a free-body diagram showing all the forces on the crate if the conveyer belt is speeding up.Homework Equations Its mastering physics says to "Draw the force vectors with their tails at the dot. The orientation of...

We experimented with the Maxwell's wheel today and at the end we were asked about why does this apparatus stop since there is conservation of energy. I did some research and apparently there is a type of friction called "rolling friction", wikipedia defines it as "the force resisting the motion...

This is a bit of a general question. Say that there's a block on a ramp, with a (massless) rope attaching it to the top of a ramp. If we're given values for the mass of the block, maximum tension, and coefficients of static and kinetic friction, how would we determine the friction or tension...

Homework Statement The coefficient of static friction is 0.604 between the two blocks shown. The coefficient of kinetic friction between the lower block and the floor is 0.104. Force F causes both blocks to cross a distance of 3.44m, starting from rest. What is the least amount of time in which...

Homework Statement [/B] A child sits on a sled (50kg) on a snowy hill with an incline of 5 degrees. The coefficient of static friction is 0.05. What downward force must a parent apply parallel to the normal force, to prevent the child from sliding down the hill? (Answer: 366N)Homework Equations...

Howdy! Could anyone advise on some high friction material combination ? I can't disclose full details of the application, but basically two flat parts a pressed together and force is applied along the plane of the joint. The pieces are about 4 square in, the force applied about 100 psi...

OK guys/gals, question of the century: What is the friction factor (K) for Dow's Molykote 3402C anti-friction coating? thanks for any insight...

Hello all. In his books on classical mechanics, David Morin claims that when computing the work W = F Δx done by a contact force that don’t involve any slipping, we can equivalently say that Δx is the displacement of the thing that is applying the force. Later, when analysing a wheel rolling...

Homework Statement Hello! I have a physics problem that I can't solve. I'm supposed to describe how I can calculate the mass when knowing the µv (I don't know the english term but I'm guessing friction...something (friction when the object is not moving)). You are allowed to use a dynamometer...

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...

Ok, so assume we have a wheel on the road traveling to the left. The wheel spins CCW and also has translation to the left. If we let the wheel roll, assuming no slip, then the translation velocity to the left will counteract the rotational velocity to the right at the bottom of the wheel, so...

I am building a rainwater collection system and want to know how much higher the tops of my PVC downspouts have to be compared to where the water exits into my rain tank. Or, how tall my rain tank can be if my downspouts are 10 feet tall. Let's say that the rain tank and home foundation are...

I have conducted an experiment that measures the velocity of an object that is moving on a flat surface. The object rolls on four fixed caster wheels. The wheels are made of some kind of rigid material. Maybe nylon, maybe hard rubber. The total mass of the object, including the wheels, is...

Homework Statement I can't understand why friction acts radially inwards when a body is rotating on a rough turntable. If the friction is removed, the body would move tangentially, hence it has slipping tendency tangential, not radially outwards, then shouldn't friction act tangentially...

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...

I read an article where the author tried to find the maximal speed a car can have when taking a turn of certain radius. They represented the car as a point and claimed that the force of friction is the centripetal force - acting perpendicular to the trajectory of the car. I do understand why...

Hi, first of all sorry... I know (close to) absolutely nothing about physics except from what I remember from school a looong time ago... :-). So, my question might sound a bit silly here. But thanks a lot for taking you time already! Homework Statement In retail business there is some...

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...

How do i suppose to determine the uncertainty for the slope of my Static friction against normal reaction graph? My data for static friction and normal force has the uncertainty of +/- 0.0001 The uncertainty is too small for me to draw airbox/bar in the graph to draw the max and min slope...

Hello Guys, I have been pondering on the nature of the frictional force and its dependency on the area of contact for the past few days and I had already searched for plausible explanations for the same.Although I could gather a few discrete points ,I couldn't get a complete picture of it. Some...