Weight Definition and 1000 Threads

So I am designing an apparatus to lift a 500g load up 500mm and I am trying to find reactions. I have filled in these values in my head with my own logic but I don't know how to do the maths and if I am right or not. I can do the initial position ok but it is the final position I am unsure of...

Homework Statement A spring has an equilibrium length of 20.0 cm and a spring constant of 51.9 N/m. The spring is connected to the underside of the roof of a car and a 0.214 kg block suspended from it. How long (in cm) is the spring when the car is at rest? How long is the spring if the car is...

Homework Statement A large weight hangs over the side of a building from a cable. The cable goes over a pulley to a horizontal roof and is attached to a small weight of half the mass. The coefficient of sliding friction between roof and the small weight is 0.5. What is the approximate...

Homework Statement Here is the question: What weight of neutral red (molecular weight 289) must be dissolved in 1.00 ml to give a =40.0 µM (µmol l-1) solution? Give your answer in MICROGRAMS (µg). Homework Equations Not sure the only one I'm aware of is mole concentration (mol dm^-3) =...

hey all, I'm stumped so I thought I'd try posting here. I am in the early stages of design of a vehicle where we have a rough approximation of weight, no idea what gear ratios or power/torque to use yet, but have an acceleration requirement. I am trying to graphically model the relationship...

Homework Statement A weight is suspended by two strings at two different angles (the picture is included in the attempted solution) a.) Find the expressions for the tension in each of the strands b.) Assuming the tension, T1, does not change, what will be the acceleration of the weight if the...

Homework Statement Calculate the gravitational force acting on a 9.6-kg mass...? 1.5 x 10^4 m above Earth's center. How do i solve this?? Homework EquationsThe Attempt at a Solution the answer is 17N but i don't understand how

What is the difference between the unit dead load and the unit weight of a material? For example, the unit weight for structural concrete is 145lb/ft^3. What would the unit dead load be? 145lb?

Hi, I'd like to know how it'd be possible to calculate the pressure inside a plastic bottle filled with water and squeezed by say 20 kg sitting on the bottle, which is lying on its side (so that resistance to deformation does't come to play as much as it'd if it was sitting on a standing...

Homework Statement A weight is attached to a wooden body with mass M=4kg lying on a horizontal surface. The coefficient of friction is μ=0.2. What is the mass m of the weight so that the wooden body is moving? Image: Homework Equations Equations of forces The Attempt at a Solution I tried...

Homework Statement Homework Equations Trig Something around the lines of this? ForceY=force(a-b)*sin(some angle) -orce(b-c)sin(some angle)+force(c-d)sin(some angle) The Attempt at a Solution Did what I did using paint. I think I am suppose to be doing something like this. Now I don't...

Homework Statement The system shown is released from rest. Mass one (0.450 kg) rests on mass two (0.820 kg) and the coefficient of static friction between the two masses is 0.560 and the same for the mass and the table. Determine the maximum mass for M(3) such that mass one will not slide on...

Homework Statement The system shown is released from rest. Mass one (0.450 kg) rests on mass two (0.820 kg) and the coefficient of static friction between the two masses is 0.560 and the same for the mass and the table. Determine the maximum mass for M3 such that the mass one will not slide on...

I don't understand why the force of weight is always positive. Doesn't gravity point down, so isn't a = g = -9.8 m/s2? I understand that people always say it's because you can choose the positive and negative directions, but why change g to be positive in these weight situations and not in...

Just wondering if apparent weight affects kinetic energy or is it only mass that affects it regardless of apparent weight? for example, a helicopter is falling but is providing a small thrust. say the helicopters mass is 50kg and it provides 100N of thrust upwards therefore, using w=mg, the...

Homework Statement 2. Homework Equations I used Lespayres equation, which is (Price of item in a year X Price of quantity of base item year)/(Price of item in base year X Price of quantity of base item year) 3. The Attempt at a Solution [/B] I was marked wrong, so I'm not sure what to do...

I had a piece of box section steel tubing, 400mm long, 5 x 10cm section, 3mm thick. It has a foot welded to the bottom which stabilises it at the floor (this is in red). It is a weight lifting bench. I needed to shorten the length, so I cut it in two and overlapped a join, then fixed it with 3...

I was lately interested in learning how the human body weight changes through out the day. Like, how much weight (may be in just 10s of grams) is lost during sleeping, after bathing, after workout and like that. For that I would require a highly precise scale. But most commercially available...

I'm in a basic level physics class as a requirement for my major. Physics has never been a strong subject for me. Can someone help me with this problem? You have a spring with a 60lb weight hanging from it. A) If the 60 pound weight stretches the spring 3 inches, how much will a 30 pound...

A toy similar to this one http://www.dhgate.com/product/novelty-toys-ufo-with-light-remote-control/135334429.html weighs 30 grammes on a digital scale. It hovers and flies. Holding the toy over the weighing scale with the motor turned on, with sufficient thrust to fly, I was astonished to...

Homework Statement Total Weight of System = 3301 kg Length, Width of Sytem = (4670mm, 1931mm) Calculated Center of Mass = (2261mm, 1065mm) Find weight at the following points: Point I (104, 1046) Point II (3182, 1867) Point III (3182, 225) Homework Equations Center of...

If two weights (Edit: hanging 10m above ground) on a frictionless pulley are equal (10kg) they will rest. If one is even slightly heavier (10.1kg) it will start to fall lifting up the other. Is final velocity dependent on the difference of weight, or it will the same as if there is no...

I'm building a sun cover for my open air atrium. Dimension is 8x8 ft. I'm building with clear cedar(ver expensive). In one direction, I'm placing 19 8ft 2x4 cedar boards tilted vertical and spaced 5 inches apart. Knowing the boards spanning 8 ft, anchored at both ends to the square frame...

Hi, I was thinking about this and hit a "wall". If you have a vertical rod with constant area that is attached to the ceiling from one point its weight will be: [itex]w(x)=ρ*x*g[\itex] (where 0 is the end of the bar) now if you take a differential above x you will have that the...

Just curious if we know what the placement of neutrons and protons are within an atom? Is one side heavier, can we determine this from polarity?

Hi pf, I have recently watched a YouTube physics video from SixtySymbols channel which is a channel of short physics videos presented by professors of physics from Nottingham University. The video (pasted below) argues that because of inertial mass and gravitational mass being equivalent this...

I know that graphene is a far more superb conductor than copper, but I'm trying to compare their weight difference. I mean, let's take an example: A copper busbar that is 7kg with resistance of 2 micro-Ω can carry a lot of current(in kA), I assume a much lighter(possible less than a kg) graphene...

I'm a mod developer and I would need some help to calculate best path/route to take for an entity. To keep this post more math related than game programming related I'll try to explain this process easily. Basicly the entity (spaceship) tries to fly in 3d-space from point A to point B and it...

I think I understand how pressure works with gases. More molecules bouncing around -> more random impacts -> stronger force. But I realized to my embarrassment that I don't understand how solid things press on each other, microscopically. Say I put a block of iron on my head. If I put...

Our company is holding a weight loss contest consisting of 5 people teams. If one of the people weigh in but can't weigh out is there a fair formula to find out what that team lost?

Hi, I am 12 years old and sort of a noob to physics due to, well, me being in the 8th grade. I need to find the weight of this spherical projectile given just about every other factor, I know the Angle in which it was fired (32.2°), the gravity of the planet this takes place on (12m/s2), the...

It is a established fact that pressure i.e ρgh will be same at a given depth. Suppose in a tank filled with water the gauge pressure works out to 1 bar, then the total pressure at the depth of tank would be 1 bar + 1 bar atmospheric pressure = 2 bar pressure. 2 bar pressure equals 2 kgf/ cm2...

Hi, I'm a first time poster here and I have a physics question I can't find the answer to anywhere. I don't know much about physics so this might be a basic question to answer. I have a mass (x) that is attached to a cable that is attached to a counterweight that is at 10 feet that will be...

Homework Statement It is given in the photo Homework Equations They are all given in the photo The Attempt at a SolutionI solved exactly the same as in the solution manual, except for the FBD of the slider B, when they write the 2nd Law, they do not input the weight there, only the...

Hi all, Can someone clarify whether the following is right? Assume a Cylindrical tank with a base area of 2000 sq.cm, is filled with water upto 15 metres ( tank starts from ground level) 1) The pressure at the bottom of tank will be 2.5 bar ( approx) i.e 1 bar pressure for every 10...

Homework Statement A person on Earth weighs 750N. What would the person weigh on a planet with 1.2 times the radius and 1.9 times the mass? Homework Equations mg=Gmme/re2 The two ms cancel, leaving: g=Gme/re2 The Attempt at a Solution Since the two ms cancel out, I thought that the...

Homework Statement A person standing on the surface of a planet has a weight of 250 N. Suppose he goes to another planet that is the same size(volume) but twice the mass(more dense). What would his weight be on the second planet? Homework Equations g=Gme/re2 The Attempt at a Solution...

Homework Statement An 80-kilogram man jumps off a raft that weighs 100 kg. His initial velocity from jumping is 7 meters per second. Assuming that the friction resistance of the water is zero, the velocity of the raft after the man jumps will be? Homework Equations Vf^2= Vi^2 + 2aD...

Homework Statement A block on a horizontal surface is attached to two springs whose other ends are fixed to walls. A light string attached to one side of the block initially lies straight across the surface. The other end of the string is free to move. There is significant friction between...

I have a simple question. If when mixing two liquids together the directions say mix 10.4 parts of hardner by weight for every 100 parts of resin and I want the final mixture to be 2.75lb, could I do the following? Mh = mass of hardener Mr = mass of resin Mh + Mr = 2.75lb Mh/Mr =...

I am designing a a robot arm based on the two degree of freedom anglepoise lamp, like the typical desk lamp or Pixar lamp, that consists of two parallelograms, each balanced with a spring. The goal is to design it so that it remains statically balanced at all positions and let two springs carry...

In my physics book the equation for apparent weight is given as FN = mg + ma where FN is the normal force, m is the mass of the object, g is the gravitational acceleration of the object (= 9.8 m/s2) and a is the acceleration of the system. For example the system could be someone standing on a...

Graduated College over thirty years ago. In physics, I recall a a question where one is required to weigh an object beyond the capacity of the scale. The answer involved resting one edge of the object on scale and the other on a separate support higher than the scale such that the object...

This is my requirement for one of my projects on E-bike. front wheel drive three wheeler with brushless DC geared motor. vehicle speed = 25 kmph Gross weight = 120 kg front wheel dia = 30 cm whether 250 Watts motor can able to achieve this requirement? What equations has to be used to find...

I have a polymer processing teacher that has decided to give us a final exam with a bunch of questions we have not covered the entire semester. I've figured out most of them but this particular one has me stumped. I am given the dimensions for a part made of a known material and need to...

Hi there, first time poster here but I've been following the forum for years - what an outstanding resource! Thanks to all who contribute. Hopefully one day I can add my 2 cents. I have a general question (more of a curiosity) that arose from an observation at work. It has sparked a debate...

Homework Statement A mass hanging on a spring is oscillating with SHM. The initial displacement due to gravity is 0.1m By considering the forces acting on the mass at equilibrium, calculate the angular frequency of the oscillations. Homework Equations \frac{d^2x}{dt^2} + {w}^{2}x = g...

Homework Statement Show that the total weight w of an assembly in thermal equilibrium is a maximum. Homework Equations S= k ln W? dS = dQ/ T ? S is maximize when thermal equilibrium is reached. The Attempt at a Solution First of all, i don't know what does "total weight w" means...

Hi all! I have entered a a water rocket competition. The rockets in this competition will be launched at 60 psi. We have to launch the rockets horizontally and to hit a round landing site 100 meters(approximately 328.084 ft) away and 30 meters (approximately 98.4252 ft) wide. I am not good at...

A 60kg student is standing on a scale in an elevator that measures weight in Newtons. Calculate the reading on the scale if the elevator is accelerating down at 4 m/s^2...when the elevator is accelerating up at 4 m/s^2... and in free fall. Not sure if my work/answer is correct accelerating...