Contact Definition and 422 Threads

Homework Statement Two small charged objects of the same mass and volume are brought into brief contact with each other. If the initial charges on the two objects are -3.00 x10^-6 and -1.50 x10^-6, what is the electric force between the objects when they are separated to a distance of 0.500m...

What is the force of contact between the two blocks? Two blocks are in contact on a horizontal table. A force is applied on one of the blocks at a 30 degree angle (from the horizontal). The system moves towards the right. M1 = 2,00 kg and m2 = 1,00 km and F=60N and the kinetic friction between...

Hi, In general maintaining eye contact talking with people creates a sense of connection, but how do you feel about maintaining eye contact when listening to complex instructions? I often find it hard to maintain eye contact if an instructor is telling me something complex (such as...

in the picture below http://tinypic.com/view.php?pic=9riq9l&s=6 if we know the angular velocity of the gear on the left, as well as their current distance from contact point, what can we say about the velocity of the right rod at the contact point at anytime t? we know it is not...

Hello. I have an exercise (not exactly homework, it's a physics contest that we are allowed to solve at home, using all possible help we can find) that goes like this: A ball with mass m = 0,10 kg falls vertically on a horizontal non-movable solid surface. Speed of the ball just before the...

This is from my textbook: I'm slightly confused about the bit underlined in red. Do you think its in reference to the sentence just before where it talks about situations of vehicles remaining tangled? (so for other cases, contact time = impact time, right?) also, I don't really...

Homework Statement Two charged spheres are brought into physical contact with each other. Initially, the charge on the first sphere was 2.34 nC, while the charge on the second sphere was -3.23 nC. a) What is the final charge (in C)on either charge?(2A) b) How many electrons moved...

Thank you for any help you are able to provide. I myself think that the electrons will flow to the human body and further drain the battery.

Can anyone explain point 44 of the attached pdf document on surface tension. (Here's the link in case attachment doesn't work: http://www.sakshieducation.com/EAMCET/QR/Physics/Jr%20Phy/12Surface%20tension%20_198-208_.pdf) How is the surface tension direction found out? Also why is...

my lecturer keeps saying that path of contact of an involute gear is straight line but without the reason. i can't digest it as i can't find the reason for this behaviour. I'm trying my best to find the reason. Internet too can't find an answer. Books don't give a timeline of how it happens. Can...

1. Homework Statement Three small identical metal spheres carry electric charges, +Q, +2Q, and +3Q. The centres of the spheres lie in a straight line at fixed positions R, S and T, such that the distance between the spheres at R and S is d1 and that between the spheres at S and T is d2. Assume...

Hi all! This isn't actually a homework question, but thought this subforum is the place for this anyway. It's been some ten years since I last touched the topic of mechanics and I guess this is a real simple question, but what can you do when I don't get it! Any help is appreciated! How do...

Hi! I am reading Molecular Driving Forces, 2nd ed., by Dill & Bromberg. On page 53, example 3.9, we consider why energy exchanges between two systems from the point of view of the 2nd law. We consider two separate systems. Each has ten particles, and each particle has two possible energy...

In rolling without slipping, why does the point of contact have zero velocity relative to the ground? If so, how can the point of contact move relatively to the ground? (It has to move relative to the ground, otherwise it cannot roll and must stay in its original position)

Hi everyone, I'm new to the forums and I don't have the knowledge you guys have about Physics, so my questions will be very simple. Yesterday I was reading a topic about using the antimatter as a weapon, and someone said it is impractical for many reasons, and he stated some, but only one got...

Homework Statement A small body is set on the surface of a smooth sphere at an angle of 45 degrees from the center. At this point the sphere is given a constant acceleration in the horizontal direction of 9.8 m/s/s. There is more in the question, but the goal is to find when the body will...

Hi there, I would like to know that if we have an leaning object supported by another object, both are supported by ground floor to satisfy static equilibrium condition, does the reaction force at the contact point produce cancelling torque (for the leaning object)? In general, can a reaction...

Homework Statement Three boxes are stacked, one on top of the other. The mass of the top box is 4kg. The mass of the middle box is 3.5kg. The mass of the bottom box is 3.0kg. What is the force exerted by the middle box on each of the other boxes? Homework Equations Fg = mg The Attempt at a...

This is a paradox that has been bothering me since I was taking algebra in high school. Let's say that I want to represent the distance between to objects. Given that numbers are infinite in both directions, by which I mean that there is no limit to how large, or small a number can be, there...

Homework Statement Two blocks of masses m1 and m2, with m1 > m2, are placed in contact with each other on a frictionless, horizontal surface. A constant horizontal force is applies to m1. a) find the magnitude of the acceleration b) determine the magnitude of the contact force between the...

Homework Statement In an experiment to determine how well benzene wets glass, benzene was found to rise to 1.71 mm in a certain capillary tube at 20.0 C. In the same tube, water rose 4.90 mm at 20.0 C. Calculate the contact angle for benzene, give that at 20.0 C, benzene = 0.879 gcm^-3...

Homework Statement If you have a system with three boxes, two side by side and one on top of the first box and there is a horizontal force acting on the boxes, do you have to account for the third box in calculating the contact force between two of them? Say if box 1, box 2, and box 3 (three...

Hi, I am trying to understand a theoretical problem involving the contact between two surfaces. I have uploaded a screen shot of the mathematical formulations of the solution. I understand most of the solution, except the principal curvatures. I have tried to look up principal curvature...

Hi all, I am currently working to build a Joule Heater that will be used to heat samples to upwards of 1000*C in seconds in vacuum. While the temperature and speed is definitely there, the contacts are always non-uniform -- making the data hardly repeatable. I am using a ~70mmx10mm Silicon...

hey i had a bizarre thought, what if there is a road made with a very smooth friction less surface and a normal asphalt road, arranged alternatively, such that , half the time spend by the tire in one rotation is placed on the smooth side and the other half on the rough side, such that the tire...

Trying to model a thermal contact between two faces. The plan is to get the heat flowing from the right part to the left part with a temperature BC on the right and convection on the left. At the moment the left part stays in the initial temperature so the contact obviously doesn't work. I...

I am asking my mentor for my class about this question, but unfortunately the answers I get from her often take forever and do not always clear things up for me, so I hope someone out there in Physics Forum has a good way of explaining this to me. Here goes... The question has some...

When ever I go trying to solve a problem, especially the ones that have my mind greatly diverge into many concepts, I seem to notice myself losing contact with logic. Its like a bad dream really. I find myself attempting to solve how I am solving a problem and so on. Or at least questioning what...

Homework Statement See attachment Homework Equations The Attempt at a Solution Ok so as the bridge is at a point ABOVE eqm acceleration is DOWN and at some point ACC down is greater than gravity acceleration. This is all true but makes no sense to logically. How could the car...

I have been working on a slightly tricky calculus problem and was hoping someone could verify my solution. Homework Statement A 4m long beam whose mass is 5 kg is attached to the wall by a wire and a hinge that allows the beam to rotate. There is a sign (with a mass of 20 kg) attached to...

Hi, My name is Rupak Karnik. I am currently a third year student in electronics engineering in Mumbai, India. I have a very keen interest in astrophysics and space sciences and I plan to pursue a career in the same. I have a mid-semester break during the months of June and July for 6 weeks...

Homework Statement The following is a worked problem from my textbook: Consider two masses, with initial tempratures T1 and T2 are placed in contact and isolated from their surroundings. They are CV1T1 + CV2T2 = CV1Tf+CV2Tf This equation can be solved for the final temprature T_f =...

Contact surface -- term Hello everyone! Help me please with selecting a correct term. The situation is as follows: There is a valve, which has a body and a bonnet. There is a joint that connects the body to the bonnet. There is a contacting surface on the bonnet flange and body flange...

Dear All, When an electrical contact is made onto the quantum well, how would the energy states be affected ?

The potential at which a metal is deposited in the electrowinning process can significantly affect the quality of the deposit. The potential itself can be dramatically affected by the addition of complexing agents and by adjusting the pH of the solution as the following calculations demonstrate...

Two soap bubbles of radius r and R are in touch find the radius of curvature of their point of contact? (Both bubbles are touching each other with their external surfaces) I have no idea about this question. can you please try to help>

\frac{x[Ain]-x[Aout][/SUB][/SUB]}{x[Ain]-x[out][/SUB][/SUB]}=\frac{\sum s^{K}-1}{\sum s^K} (1) for k = 0 to n Final result...

A cylinde with a piston in contact with a heat reservoir at 353 k. While keeping this gas at constant temp and pressure of 1.01 x 10E5 n/m2 we permit he gas to expand by 1.5E-5 m3. How much heat does the gas absorb? Is it just p x v = w and w = q to get an answer of 1.15 j? Cause i feel like...

I have calculated a static contact stress of 670 N/mm2 using formula from Mechanical Engineering Design, Shigley, 5th Edition. My problems lies that there is no acceptance criteria. I'm using Grade 5 Structural Steel (yield~355 N/mm2). Previous threads have stated that a 2.5 * yield can...

Hi I was just wondering what ways you can smash glass without physically touching/breaking/throwing something at it. For example, I know that the "force" of an explosion can break glass that is a fair distance away from the actual explosion. So is there any way you could make something that...

Hi this is a problem from my midterm at the beginning of the quarter and i have a final coming up so i need to know the previous midterm material but i still don't understand this one question. Dave suddenly drops from the wire and lands at a velocity of 2m/s on some cardboard boxes that...

For my Project, two angular contact bearings are selected to support a spindle. However, I would like to preload both the bearings considering thermla expansion.. I would like to know the max. permissible preloading limits for the bearings. Could someone suggest me some good material or links to...

My teacher said there isn't a special kind of formula, you just derive it from f=ma. This is the diagram:

Homework Statement A nearsighted person has near and far points of 11.0 and 22.0 cm , respectively. If she puts on contact lenses with power P = -4.00 D, what are her new near and far points? Homework Equations P=1/f 1/f=1/do+1/di where f=focal point, do=distance to object...

What happens when two objects of different charges come into contact? Do they distribute the charges per mass, volume, surface area or something else?

"If there's no normal force, there's no contact." Is the statement above correct? What is the relationship between contact and the existence of normal force? Are they necessary and sufficient conditions to each other? Thanks for your help :p

1. What happens when two spinning disks collide? Suppose you have two flat, thin disks with uniformly distributed masses m1 and m2, moving at angular velocities ω1 and ω2. the two objects are brought together edge to edge, ie they collide. obviously as a result of this collision, the objects'...

Hi All I recently purchased a 1000w heating element for coffee cups, http://www.ebay.com.au/itm/110668421004 that I will be using on a 240v AC source. I would like to know if a cup out of silicone will withstand direct contact with the element? From what I am reading normal silicone...

Hello! I know that the contact force formula is Fc = F(m2/(m1+m2)) but I was wondering, how did this equation come into being? How is it derived? No this is not a homework question, I was just curious to know. Thanks!

Homework Statement A 0.25 kg ball, initially at rest, is hit with a bat in the x-direction while held 1.00 meter above the ground. If the ball hits the ground 20 meters away and was in contact with the bat for 0.10 sec, What average force was exerted on the ball during the contact time...