Pull Definition and 312 Threads

When a magnet pulls a paperclip, what exactly is doing work on the paperclip? It cannot be a magnetic force can it? I thought it was a very strong statement that I read in my intro physics book and even Griffiths(pg. 207) that magnetic forces do no work. So what is responsible for accelerating a...

A question has arisen (not homework) showing two pulley systems and a box being pulled up with a man pulling each. The question asks who has to pull hardest. On one of them (A) the shafts (supporting the rope) are smaller whilst on the other (B) they are larger. The correct answer is that the...

I have been looking into dark matter recently, and I have three questions. When calculating what the gravitational pull of an object should be, do they account only for the mass of that object, or do they account for the total energy of that object? For example, a star will have a lot of mass...

Homework Statement A bit of asteroid material of mass 2.5 x 10^6 kg orbits around the Earth at an altitude of 2800km. How long does it take the asteroid to complete one orbit. M asteroid = 2.5 x 10^6 kg altitude of asteroid = 2800 km radius asteroid = 200m radius Earth = 6.37 x 10^6 m...

Hello, I am looking to install a pull up bar in my home. I have a 6' 4" span. I weigh 200lb. I'd like the bar to have a round cross section so that I can grip it directly. Ideally the outside diameter of the pipe should be 1.25". I don't want there to be too much spring or give in the...

Hi all. I am going to build an industrial quality knife-tool to cut cardboard, and I would like to ask you all for any advice, experience and warnings you might have. I'm in the need of a motor to oscillate a knife at a frequency of 200-300 Hz, with a stroke of 1.2mm +/- 0.6mm. The knife it...

Homework Statement A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling. One end is held by student A (70 kg) who is at rest. The other side has student b (60 kg). I need to explain why or why not student b can lift student a off of the ground if he...

hi there i have been reading up on the function of pull up resistors from the text:http://ti.tuwien.ac.at/ecs/teaching/courses/mclu/theory-material/Microcontroller.pdf and on page 37 it talks about it. in their example of the pull up resistor with the switch. i was wondering if they circuit...

Homework Statement a parallel plate capacitor of 10pF is charged to 10kV ( air dielectric). It is then isolated from battery.The plates are pulled away from each other until distance is 10 times more than before. what is the energy needed to pull the plates. Homework Equations c=εA/d ...

Homework Statement The wire shown is being pulled through a constant magnetic field of 0.25 Tesla at 3 m/s. A) Find the power required to pull the loop at this speed. B) If the wire has a resistance of 100 ohms, what is the current in the wire? Homework Equations The Attempt at...

Why does tidal force strectechs the Earth and creates two tidal bulges, like pulling on a rubber band, instead of pulling Earth and moon together?

Homework Statement I'm given the mass of the object and acceleration (gravity), and I'm given the pull back distance of one test of the slingshot. I've found the k constant by finding force with f=ma, but I need to find the pull back distance using the same slingshot in order to propel the...

Hi everyone, I have this following problem (uploaded it in the pdf). I have made an attempt at solving it, but now i am just stuck. I have done question one, and have confirmed my answers in PSpice. my Id = 16uA, Vgs = 1.4V and Vds = 4.6V ( 3 + 8/5) and for p-channel the values are...

Calculate the pull on the high bar of a gymnast performing a giant swing. His angular velocity is 2 rads, his mass 80 kg and effector radius of rotation (distance from bar to CofG) is 1 meter Hi... I am a bit confused... "pull on the bar" would this be the work done on the bar to the person...

Homework Statement You're using a rope to pull a sled at constant velocity across level snow,with coefficient of kinetic friction 0.050 between sled and the snow. The sled is loaded with physics books, giving a total mass of 19 {\rm kg}. Homework Equations F=\mu*n The Attempt at a Solution...

If one had a high enough electric field could one pull electrons and positrons into existence out of the vacuum? The field needs to be high enough to accelerate the virtual particles away from each other strongly enough so they don't get a chance to recombine. If a particle has...

what are pull up and pull down resistors i read that i have to connect pull up resistors with microcontroller why they are called pull up resistors and not simple resistors?

My name is Derek Cox, I am new to the forum and I am not an engineer or anything close. I have a degree in flight management and I am a commercial plumber that works on large scale construction projects. Here are my questions but first I will give you some background on the questions. I am...

forgetting the need to enter an orbit, is there a difference in the energy required to escape the Earth's gravity by firing a rocket straight up against firing a rocket on a trajectory? Straight up would be a shorter distance.

Homework Statement prime mover = 220 hp crane = 2000 tonne velocity crane = 10m/min = 0.17m/sec acceleration crane = 0.017m/sec every 100 tonne = 6 tonne of friction 1hp = 726 W 1 tonne = 1000 kg Homework Equations how many prime mover are needed to pull the crane?prime...

we know that on Earth, an object falling with a rate of g horizontally, and the formula for it is a=g*cos x. So according to GR, an object falls into the warp of space time that a huge object causes. So should there be a new "g" applied to all the warp in space time? Am i right or not?

Hi PF, A disclaimer, I am no good at Physics or math. My question: When calculating the pull force between two magnets it seems to always be calculated at an angle perpendicular to the surface of the magnet. I was wondering what effect on the force required to "pull" one magnet away...

Hello all. I'm not knowledgeable in this area so forgive me if this question is obvious. Just a thought which occurred to me that I don't know how to answer. Here is what I'm envisioning: picture a wheel, and an attached rope which is perpendicular to the plane of the wheel. If I pull on the...

1. The left end of a spring is attached to a wall, When Bob pulls on the right end with a 200N force, he stretches the spring my 20cm. The same spring is then used for a tug-of-war between Bob and Carlos. Each pulls on his end of the spring with a 200N force. How far does Bob's end of the spring...

What is the most energy efficient way to disrupt 20 lbs of magnetic pull? I'm trying to separate two magnets the most energy efficient way possible. One idea I had was to use the velocity of kinetic energy to quickly insert mu-metal between two magnets. Or is it better to slowly insert mu-metal?

Self Propelled Golf "Pull" Cart Hello everyone. I am quite the novice when it comes to stuff like this but I was wondering if anyone would be able to help me with a project I would like to undertake. My idea is to build a golf “pull” cart with some sort of DC motor that might run off a battery...

Homework Statement Prove that the horizontal force needed to pull two weightless, thin hemispheres apart has magnitude F = \pi*r^2 * \Delta p where \Delta p is the pressure difference between the inside and outside of the spheres. Homework Equations surface area = 4\pir^2 F = pA The...

i have a electromagnet with 200# pull is their a way to get full pull on sheetmetal or is their something i can do to the sheetmetal.

Homework Statement Please see attachment. Homework Equations E=vB F=qVB The Attempt at a Solution My question is the last part "which of the following are true". I've tried these choices and all were wrong: (1, 2, 3) (1, 2) (2) (1, 3) I really am confused. I swear 1 is...

The box weighs 400lb and the person can pull with 200 lb of force. Will this person be able to raise the box? What is the maximum weight he can life using the pulley system? Sorry i couldn't figure out how to start. Appreciate any help, Thanks!

Dear Friends & Colleagues, I would like to propose the following Question, Is there a way to technically Measure the Gravitational Pull of a body? (body being any of the following: molecule, physical item like a rock, or a planet or a star). I am not looking for a sample of a falling...

I am working on my own laws of physics because I am extremely bored. I am making a law or revolution (objects revolving around other objects) and thought of a few questions that hopefull you guys can help me with. Here they are... 1) In a vacuum, where the only gravitation pull is between you...

A boy is sitting on a sled that is 100kg. If you pull the sled forward for 20 meters, your avg. force is 500N. How much work did you do at that time? (no friction on the ice/snow). What was your avg. acceleration? Help for Force, Impulse and Momentum Thanks!

Homework Statement Sled dog to pull on a snowy sleigh horizontal road, the mass of its load is 210 kg. Snow and sleigh runners movement between the friction coefficient is 0.095. Dogs sleigh force exerted by the horizontal. acceleration of 0.13 m/s2? Gravitational acceleration is 9.81 m/s2...

Homework Statement find 2 power series solutions of the given diff eq about the ordinary point x = 0 y'' - xy = 0 Homework Equations y = (c_0)(y_1)[x] + (c_1)(y_2)[x] The Attempt at a Solution i can set it up to this (sorry idk out how to insert the subscripts with the summation symbols)...

A lift electromagnet has N + S pole on the same side. will it push or pull a permanent magnet which has N & S pole on opposite side? If I have a lift electromagnet and a permanent magnet, both can pull 100 lbs. What is the break away force if I put them together? Thanks

I have been working on an idea for a little while.. A large hurdle in planning for this idea is that I need to figure out what the net gravitational pull would be on a 17,200km long cable going from a geosynchronous orbit around Mars to the surface of the planet would be. Its basically...

hi all i'm a high school student doing a physics experiment about the peeling force of a tape. I want to see the realtionship between the peeling force and the peeling velocity but I cannot think of a good way to pull at constant speed. I tried to connect the spring to a motor so that the...

Hello, I am new to the forums and having a discussion with my boss at work regarding when you are pushing something and when you are pulling something. We are writing curriculum for training and aren't completely sure when to say push and when to say pull. It isn't that difficult, I know, but...

Homework Statement A man wishes to pull a crate 15m across a rough floor by exerting a force of 100N. The coefficient of kinetic friction is 0.25. For the man to do the least amount of work, the angle between the force and the horizontal should be: Homework Equations W=Fd; frictional...

Okay, so here's the though process that led me to ask this question. We know that the speed of light through a vacuum is constant. Yet if we have a ray of light that passes by earth, or any other large massive object, the light is bent. Gravity pulls on the light, apparently. But how can...

Homework Statement http://i1046.photobucket.com/albums/b465/laurenwings5/Picture1-1.jpg Two planets with the same diameter are close to each other, as shown. One planet has twice the mass as the other planet. At which locations would both planets’ gravitational force pull on you in the...

Homework Statement Two identical blocks of mass m are attached via a massless spring of spring constant k. The length of the spring in equilibrium is l. The system moves on a frictionless horizontal plane. With one block resting against a wall, the two blocks are pushed to- gether, so...

Homework Statement A constant horizontal pull acts on a sled on a horizontal frictionless ice pond. The sled starts from rest. When the pull acts over a distance x, the sled acquires a speed v and a kinetic energy K. If the same pull instead acts over twice this distance, <the sled's speed will...

When a neutron star flucuates into a black hole does the gravity increase tenfold? Or does the neutron star gravity (while turning into a black hole) increase as expected with the addition of more mass?

Homework Statement A man is strapped to a chair which is connected to a pulley (combined weight of chair and person = 95 kilograms). With what magnitude must the man pull on the rope if he is to rise a) with a constant velocity b) with an upwards velocity of 1.3 meters per seconds...

Hi, I am trying to program an I2C interface and it's not working. The master is TI Cortex M3 processor and slave is ST Compass. I have captured the scope pictures and found that slave is not bringing the data line all the way to ground and this is violating I2C spec. I have sent the scope...

Let's say a magnet is attached to an object that weigh's 15 pound's . Then someone attempt's to take the magnet off the object . The object then go's up with the magnet (still being attached to it ) Does that mean the magnet can lift 15 pound's ? Also when a magnet is rotateing through a coil...

Hello everyone. I have been trying to determine the tensile force needed to rip a threaded tube out of its female threaded socket. After some Google searching, I found this: http://www.engineersedge.com/thread_strength/thread_bolt_stress.htm I used shear area, which I believed to be an...

Homework Statement The yo-yo is made of two wheels, connected by a short beam (the cross-section of the beam looks like the letter "H"), around which wire is wrapped up. Let the yo-yo be stationary on a desk. What is the angle ß in relation to the said desk (see picture) that we must gently...