Sliding Definition and 733 Threads

I have just watched a video lecture about the Tomlinson model (aka Prandtl–Tomlinson Model) which explains the friction mechanism at a nanoscale by analogy with a tip dragged by a spring. The video has prompted me to ask several questions. The spring is dragged over a corrugated substrate, as...

I thought in this equations f is the man's pull\ f + dm*g = T < 600 Where dm is equal to the mass of the string that pull the up part (15-x) after descending x meters. dm/(15-x) = m/15 And, to the man: W - f = Mx'' I can solve this, and i got ~8m/s Is this right?

i have no idea how did the answer come in conclusion...i guess that cosθ and sinθ is referring to the 2 dimensions of the acceleration ? but how? and why?

Dear, Could you tell me if the calculations on the attachment are correct? I need to determine the force necessary to prevent the clamp from slipping. Basically the clamp is a part of rubber that I can press against the pipe wall. A load will be attached to this part of rubber. The tube is...

I got the correct answer for the first part but I'm not sure why the answer for (b) is the same for (a). Wouldn't the rings falling off mean that I_f = \frac{1}{12}M_L L^2 only where I_F, M_L, L are the final moment of inertia, mass of the rod and length of the rod as opposed to I_f =...

I learned that rolling involves the coefficient of static friction unlike sliding that involves the coefficient of kinetic friction. It's known that the coefficient of static friction is always higher than the coefficient of kinetic friction. This should result in rolling to be more difficult...

On the left: my copy of the illustration in the problem. On the right: top view, with the angle. The problem gives the magnitude of the magnetic field, the radius of the rail, the resistance of the resistor, the initial rotational frequency of the bar. I am able to obtain the given solutions...

This article from Science Advances (probably not open access, an AAAS publication) has described a complex and interesting molecular mechanism (a nano-bio-molecular machine). A rotary motor in the cell membrane (driving mechanisms unknown) spins a gear that pushes a "tread" along a track imbeded...

The truck stops in a shorter distance if the crate slides but why is this the case considering that friction on the crate does positive work on the truck, since it points left for the crate but right for the truck thereby opposing the braking force? I understand why using the equation 1/2mv^2 =...

Hi everyone! Sorry if I'm not able to work through this problem very much myself... I'm a Food Science student, and I'm trying to read an article about ultrasonic cutting when applied to apple slicing. From the papers they reference, the rapid vibrations on the blade reduce the friction...

I initially thought it is v, because the speed shouldn't change when the tape is on top.

Hi! First of all, mention that this is not a "homework" problem in the sense that no teacher ever gave it to me or that I have the obligation to do it. It is a question that came to mind when repasing the theory done in class and though interesting. I still post it here because I suppose that...

Homework Statement: A perfect hemisphere of frictionless ice has radius R=6.5 meters. Sitting on the top of the ice, motionless, is a box of mass m=6 kg. The box starts to slide to the right, down the sloping surface of the ice. After it has moved by an angle 20 degrees from the top, how much...

Figure A It slopes up from Left to Right (0.205911m Rise /4,8m run=4.28%)]

Question as follows: My answer/explanation: Force needed to make block slide = static friction between block and plate. So friction = normal of block * static friction = (0.5∗9.8)∗0.9=4.41N(0.5∗9.8)∗0.9=4.41N My thoughts/wrong answer probably?: after block slips, plate experience kinetic...

Sol: ##Mg.sinθ - μMg.cosθ = ma## ##a = g.sinθ - μg.cosθ## Now ##S = ut + \large\frac{1}{2}\normalsize at^{2}## but ##u = 0## ##t = \large\sqrt\frac{2s}{a} = \sqrt\frac {2s}{gcosθ(tanθ- μ)}## My questions: What is the meaning of " PQ = s" in the question? How ##t = \large\sqrt\frac{2s}{a}...

A dumbbell consisting of two weights of mass m and a bar connecting them of length L is sliding down a frictionless wall and floor, with one weight on the wall and one on the floor. The dumbbell starts sliding from rest. Find the speed of the two weights when they are equal in speed. I tried...

Recently I've come across a question that seems very simple, but had puzzled me for a while. Suppose a point object with mass M is placed on a rough plane inclined at 30 degree to the horizontal and is subjected to the force of gravity acting down vertically (to make it simple, assume g = 10...

I don't really understand if the initial horizontal velocity is 0? Or do I assume it's some constant? Putting aside vertical velocity. Also how should the "mechanical work done by gravity" be calculated? Is it just ##W = \frac{1}{2}mv^2_{final} - \frac{1}{2}mv^2_{initial}##

emf = dΦ/dt = (B*A)*d/dt = B(dA/dt), dA/dt= L*d/dt(vt) = L*v, emf = B*L*v per coil Since there are 25 loops the total emf= 25(vBL) This is where I'm am stuck. Would I assume that B is 24 uT, the velocity as 3m/s , and the length as 1mm? If so I would get ∆V as 1.8*10^-6.

How would you model the following situation? A man of mass m slides on rough ice with coefficient of kinetic friction ##\mu_k##, while pushing outwards at intervals to try to come to a stop in a shorter time. For example, he might slide for 5 seconds then push out with his right foot, then...

I think I am on the right path but I'm having trouble cancelling out the mass of the wallet. I drew a free body diagram and know that there are three forces acting on the wallet: gravity, friction, and normal force (including the van's acceleration). The y-component of the friction and normal...

W_net = Integral from 0 to 0.70 meters [ - F_spring - F_friction ] = 1/2 * (-k) * x^2 - mu * mg * normal force * x = 1/2 * (-325N/m) * (.70)^2 - 0.250 * 6kg * 9.81m/s^2 * 0.70 - 0 = - 89.93 Joules Is this correct and am I setting this whole thing up correctly? The negative signs have me...

Homework Statement To lift a box it needs 250N force (F). How much work (A) has to be done to lift it at height (h) 1.2m and to slide it horizontaly (l) 1.2m. Coefficient of friction is 0.2 (μ) F = 250N h = 1.2m l = 1.2m μ = 0.2 A = ? on both situations 2. Homework Equations A = F * h A = F *...

Homework Statement The 2 objects slid on the incline level without friction. The height difference of the objects at t=0 is 8m. At t'=1.5sec the objects are on the same horizontal level. What is the analogy of M/m? (M is the mass of the left object and m the mass of the right object. *Have a...

Homework Statement Not an actual homework problem but a discussion that came up in class while we were learning about torque. A tall box is sliding across a surface with friction f, mass m, and velocity v. What equations would you use to figure out if the box would tip over while sliding to a...

Homework Statement Two particles A and B are connected by a rigid rod AB which slides along two mutually perpendicular rails as shown. H is the angle between point B and the horizontal rod. At an instant, when H=30°, the velocity of B is 10m/s towards left, and velocity of A is upwards. Find...

So I need to find equations for the force required to tip over a cylindrical object. This is fairly straight forward in the case when the force is applied above the centre of mass, by taking moments about the pivot corner. However, in the case where the force is applied below the centre of mass...

Homework Statement [/B] This problem is from David Morin's Introduction to Classical Mechanics, Chapter 3, Problem 7: A block is placed on a plane inclined at angle θ. The coefficient of friction between the block and the plane is μ = tan θ. The block is given a kick so that it initially moves...

Hey! I've been trying to figure out these two problems but can't seem to get the right answer. Was wondering if someone could help me out? 1. A block is pressed against a vertical wall by a force F, as the drawing shows. This force can either push the block upward at a constant velocity or...

Homework Statement A force of 180 N is required to slide a loaded box along a horizontal floor. If the coefficient of friction is 0.32, what is the weight of the box? The Attempt at a Solution I'm not knowledgeable about any solutions able to retrieve the correct answer since the mass of the...

Homework Statement We kick a box upwards a ramp. The box slides upwards, then slides backwards again. We ignore the air drag and other factors. We only look at the gravity, normal forces and friction forces. Forces on the box when it's moving upwards: Weight of the box is 0.123 KGs. Angle...

Homework Statement Three identical 4 kg crates are stacked one on top of the other. You want to accelerate them as much as possible by pushing on the lower crate, but the forces of static friction between the surfaces of the crates max out at 25 N. What is the maximum acceleration you can...

1. Homework Statement in picture Homework EquationsThe Attempt at a Solution in picture, not sure if i am even doing this properly but i think i am? i am going to continue trying part b but please if you can let me know if i am doing this proper let me know...Thank you

Homework Statement A child of an Eskimo decided to slide down an igloo. The igloo looks like a hemisphere with radius R. When will the child fall off the slide? Homework Equations See belowThe Attempt at a Solution There are only two forces acting on the child - the force of gravity and the...

A frictionless incline (the triangle below) is bolted to the floor so that it can not move. A block of mass m slides down the slope, which makes an angle with the horizontal.a)Draw a free-body diagram for the block, labeling all forces uniquely. b)Describe all the forces listed above in the...

Homework Statement A bead slides under the influence of gravity on the frictionless interior surface of the paraboloid of revolution z = (x^2+y^2)/2a = r^2/2a Find the speed v_0 at which the bead will move in a horizontal circle of radius r_0 Find the frequency of small radial...

Hi, from this excellent book https://www.amazon.com/dp/0443035288/?tag=pfamazon01-20

Homework Statement An object which has mass = m is released from point A which has height of h. The object moves along the rail with no friction. The rail OB is a semicircular rail which C is the center and R is the radius. If the object falls from the rail at the point B, find the following...

Homework Statement A block with a mass of 820 g starts from rest at the top of an inclined plane that is 106 cm long and makes an angle of 49.5 degrees with the horizontal. It accelerates uniformly down the ramp and reaches the bottom in 0.89 s. What is the coefficient of kinetic friction on...

If someone was sliding down a vertical pole (like a firefighter) would only friction need to be considered to find out how fast the person is "falling" or is there also normal force from where the person is touching the pole, and would that affect the person's speed down? (I am ignoring air...

Homework Statement Hello. I have this problem: I have a ring which is sliding along a wire in the shape of a spiral because of gravity. Spiral (helix) is given as the intersection of two surfaces: x = a*cos(kz), y = a*sin(kz). The gravity field has the z axis direction. I have to find motion...

I have been watching videos on the brachistochrone curve and from my understanding, the curve works as the ball goes through more acceleration at start, therefore causing it to reach the end the fastest. However, I understand that acceleration towards Earth is constant (9.81 m/s^2) and this...

Homework Statement An object of mass m=2 kg slides down on a track from a height of h = 10 m. The track is frictionless except the horizontal range between the points A and B. The friction force is constant between A and B. What is the speed of the object at point B if the magnitude of the...

Hi, I have a 2nd order of sliding mode observer of the form: \dot{\hat{x}} = \hat{f}(x,t) + \delta f + \Psi(u,y) +[ \frac{d \Omega}{dx}]^{-1} \upsilon where ##\upsilon##: \upsilon_1= \alpha_1 \lambda_1^{1/2} | y_1 -\hat{x}_1|^{1/2}*sign(y_1 -\hat{x}_1) \upsilon_2= \alpha_2...

I am currently working on this problem and I am stuck as to how to approach or solve it. The problem is that a block of mass 11000kg is sliding down a slope with a height of 1000m, angle of 40 degrees and the coefficient of friction between the block and the slope is 0.1. The block splits...

Homework Statement A mass point is sliding down from the top of a hemisphere, with an initial speed of zero. I want to determine the angle ##\theta## at which the mass point will lift off the surface of the hemisphere. Homework EquationsThe Attempt at a Solution We can determine the speed...

Homework Statement ( The following problem is taken from kleppner's " Introduction to mechanics" ) ( The question in the book talks about the velocity but my confusion is related to the Energy ) Homework Equations Conservation of Mechanical energy : Ef - Ei = 0 Consevation of Momentum : Pf -...

1. The problem statement, all variables, and given/known data A block with an initial speed of 20.0m/s slides up a ramp with an incline angle of 30º. (a) (2 points) Write the position as a function of time for motion up the surface of the ramp. (b) (2 points) Write the velocity as a function...