# friction

1. ### Mechanics: Slope Friction Problem

So far, I have this: For Part ii) I know that: mgh = xmgsin(theta), but I don't know how to go further
2. ### B Friction and surface area

From what I read on the internet I found that increase in surface area that is in contact is offset by the reduction in pressure. What exactly does it mean? This is what I understood from the it (but my understanding might be absurd :-p): does reduction in pressure mean that the "hills" or...
3. ### Problem involving friction, with a mass being pulled up a slope

(The answer from the markscheme is 26.7)
4. ### Kinetic friction coefficient of aluminum on lubricated cast iron

Hey all, I was recently searching for kinetic friction coefficients, and I noticed that for a reason which is unknown to me, some materials had not been appointed such coefficient. The specific kinetic friction coefficient that I'm looking for is aluminum on greasy/lubricated cast iron. Any type...
5. ### AP Physics 1 Help? Centripetal motion/Kinematics/Friction problem

I think I have solved the first three, and only really need help on question four. For number one, I used Fc = (Mv^2)/R and just rearranged it for velocity so I ended up with v = sqrt(ac * R) For number 2 I used Ff = Fn*mu and got Mg*mu = Ff For number 3 I used w = Ff*d and got w = -Mg*mu*l...
6. ### B Resistive force that a nail will have to overcome to penetrate a piece of wood

lets say a hammer of 0.5kg strikes a nail at 10m/s. The nail penetrates into the wood by 1cm. The reason why the nail stops is because friction has eventually overcome the nails momentum. The retardation of the nail can be worked out, but Can you calculate the force that stops the nail if you...
7. ### Velocity of an object on an inclined plane

I used work energy theorem between initial top point and point x along the incline(downwards) i got the expression of v then diffrentiated it to get a maxima but it gives me a wrong ans which is 10/6 but the actual ans is 10/3 please tell me what i did wrong

9. ### Saw characteristics influencing efficiency in sawing steel?

Hello, I am having a headache to try understand a possibly simple real-world problem: efficiency (as in number of strokes/cumulative length needed) to saw steel, assuming a constant sawing length per stroke and a known steel sectional area. I began to think about the few assumptions I assume...
10. ### Car braking before a wall

1. For the car to apply brakes, we have $v^2=2ar⇒a=\frac{v^2}{2r}=μg\;\;[ma=μmg]⇒v=\sqrt{2μgr}$ 2. For the car to go in a circle $\frac{mv^2}{r}=μmg\Rightarrow v=\sqrt{\mu gr}$. We find from above that the maximum velocity $v$ possible to avoid a collision is $\sqrt{2}$ times as much...

20. ### B What exactly is limiting frictional force?

Given that a body is moving with a constant velocity on a rough surface. Is it possible to say that if the force (which keeps the body moving with a constant velocity) is withdrawn then the rate at which it will decelerate = limiting frictional force / mass of the body? {Force = m * a}. Thank you.
21. ### Find Velocity of the wooden block at t=4 sec

Here's the given F-t graph My Attempt..... Fsmax=10N & Fk= 5N I made equatiom F=5t-5 ( by seeing Force force and Counteracting kinetic friction) reduced the formula to a=(5t-t)/2 wrote a=dv/dt and solved it but got wrong answer.
22. ### A How does 1-wheeled motorcycle turn?

I've witnessed 1st-hand with my own eyeballs this guy riding an S-shaped path through chicane at Thunderhill East+West 5-mile combined course with front-wheel IN THE AIR! I believe bike is a Yamaha TZ250, 100-120bhp and 200-lbs weight. I conducted an experiment to document behavior of single...
23. ### Rotating with slipping to rotating without slipping?

It seems to me that this transition implies going from kinetic friction to static friction. The kinetic friction would apply a torque that would slow down the object's angular velocity, but I'm not sure how this connects to the object suddenly transitioning into rotating without slipping.
24. ### Modeling Hydraulic Brake Behavior

Summary: Relation between deformed foil and friction force Good morning everyone, i have a small leaf or steel that is bent from one side by a Pressure of many bars. in front of the leaf there's a rotating disk, separated by the leaf by a small gap. this leaf, as it deforms, wins the gaps and...
25. ### Energy and non-conservative forces

I feel like it would go on the side of the energy the object has where it starts - an object dropped off a cliff would be modeled U - W = K but an object thrown upwards from ground level would be K - W = U. I am not sure though.
26. ### Time needed for a Force F to accelerate the crate to 2m/s? (Dynamics)

So above is the question. The picture below is my attempt at the solution: However the answer at the back of the book suggest that T=1.929s
27. ### Acceleration needed to keep an object from sliding down a windshield

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...
28. ### Explain friction in a pulley system

Hi! I'm working in a new area and I'm looking for inputs/suggestions for relevant factors to look into and possible ressource where I can read about this :) I did some tests in a pulley similar to the one below. I had a fixed weight at M2. I started with M1=M2 but added weights to M1 until...
29. ### How to calculate the work done

Homework Statement A sledge loaded with bricks has a total mass of 18.0 kg and is pulled at constant speed by a rope inclined at 20.0° above the horizontal. The sledge moves a distance of 20.0 m on a horizontal surface. The coefficient of kinetic friction between the sledge and surface is...
30. ### Free body diagram problem

Hello everyone. I find the following problem confusing. A board sandwiched between two boards in the figure below weighs 95.5N. If friction exists between the middle and the compressing boards, draw the free body diagram of the middle board. Below I attached the diagram found in the solution...