Weight Definition and 1000 Threads

  1. F

    Suspending a Weight with 3 Cords: A Puzzle

    Homework Statement Weight suspended by 3 cords. 1 from the weight goes up vertically to the knot. The next goes left 30° below horizontal and the last goes to the right 45° above horizontal. Homework Equations f=ma The Attempt at a Solution I don't think I've ever worked a problem...
  2. J

    How Weight of Flywheel Changes in a Gravity Well

    A spinning flywheel is lowered into a gravity well using an elevator. Energy flows from the flywheel into the elevator motor (which functions as a generator in this case). The energy is red shifted by gravity, and equivalently by centrifugal force. To be more specific the force part of...
  3. S

    The weight of an astronaut during take off?

    Homework Statement A spaceship accelerates with constant acceleration to 120 m / s within 10 seconds after launch from Earth. Imagine that one of the astronauts who weighs 77 kg sits on a bathroom scale while the Launch takes place. What does the scale show during the launch ? Homework...
  4. Dembadon

    Is Heavier Always Better? Exploring Our Bias for Weight in Everyday Objects

    I find I'm biased towards heavy things. I realize this is unreasonable, as a heavier object will not always be of better quality, but I still find that I prefer a heftier object even they wouldn't necessarily benefit from it. Here are some examples of some things I prefer to be heavy: bed...
  5. M

    Is it possible for a long hair to having heavy weight?

    http://www.odditycentral.com/pics/tran-van-hay-the-man-with-the-worlds-longest-hair-dies-at-79.html The man is reported to have the longest hair in the world, they claimed that his hair was measured at 6.8 meters long but never been measured officially. But what I'm skeptical about this was...
  6. E

    Acceleration in a Weight Machine

    Homework Statement An Atwood's machine consists of two masses, m1 and m2, connected by a string that passes over a pulley. If the pulley is a disk of radius R and mass M, find the acceleration of the masses. Express your answers in terms of variables m1,m2, M, R, and appropriate constants...
  7. B

    Pulley question to determine the weight at a certain angle

    Homework Statement An assembly shown in the picture, GH , HK, HNL are three cables. the mass of box L is 52Kg, a) determine the mass of box K in order to make angle theta as 25 degrees Homework Equations Fx=0 Fy=0 The Attempt at a Solution Fhn x cos(25) = Fhg x cos(0) fhn x...
  8. E

    Weight of an object sliding on an incline

    First I would like to appologize for my english, I'm from belgium and I don't often use it to speak about physics. Second, I don't know if I'm in the good thread to speak about that. Ok, I need a little help, I have a problem where an object slidind on a incline plan. I would like to know...
  9. Gh778

    How does rotation affect weight changes?

    Hi, The weight on Earth is F = m*g with g = G*M/(r+h)² with G = 6,6742 e-11, M mass of Earth and r the altitude or radius of Earth and h local altitude. M = 5,9736e24 kg. r = 6371000 m. With 2 masses M1 and M2 of 1kg each at altitude h = 0 m, the weight is g*2 = 2*9.82245719295718826387 =...
  10. T

    Admissions Grad Admissions: How Much Does Sub-Department Matter?

    I'm browsing through some acceptances posted by prospective graduate students here: http://www.physicsgre.com/viewtopic.php?f=3&t=4274 and there are some guys with very close to 4.0 GPAs and great GRE scores along with pretty good research experiences and letters of recommendations that are...
  11. S

    What Fraction Of Her True Weight Was Indicated?

    Homework Statement Julie tightened herself fastened a set of bathroom spring scales to a platform and went down a 30 degree slope. No friction was present and the platform supporting the scales was HORIZONTAL. what fraction of her true weight was indicated by the scales? The Attempt...
  12. J

    How Is the Weight of a Bird Calculated When It Sits on a Kite?

    Homework Statement A man is flying a kite. The string of the kite makes an angle of 50 degrees with respect to the horizontal and exerts a pull of 15 Newtons. A small bird decides to sit on the kite and causes the kite to reach a new equilibrium position with the sting at 30 degrees with...
  13. M

    Can Earth sustain much bigger object with an infinite weight?

    I know this question maybe a bit funny, others will call this post BS. But just assume if any object, having a size that ten times larger than Earth and having infinite weight, can the Earth resist such pressure? I recalled somewhere mentioned that Earth, theoretically, can support weight...
  14. Z

    Which pulley system requires the least force to lift the same weight?

    Homework Statement http://data.imagup.com/10/1146555432.jpg Homework Equations Force applied on the weight=F*(MA). The Attempt at a Solution i chosse the E system ...it has the greater mechanical advantage (MA)=3. MA(of A)=1, MA(of B)=2,MA(C)=2,MA(D)=2,MA(E)=3.. I hope my...
  15. E

    Weight on a Scale Down an Incline vs. True Weight

    Weight on a Scale Down an Incline vs. True Weight Homework Statement Judy fastened a set of bathroom spring scales to a wedge shaped skate board as shown and coasted freely down a 30 degree slope. The wheels were well oiled and the platform supporting the scales was horizontal. What...
  16. M

    Force and acceleration leading to weight of a parachutist

    Homework Statement http://www.physics.ox.ac.uk/olympiad/Downloads/PastPapers/BPhO_PC_2008_QP.pdf Question 8 Homework Equations f=ma The Attempt at a Solution Sure since f=ma A) would have force of 0, since there is no acceleration B) force would be 800N C) force of 0N D)...
  17. M

    A Question About Weight and Pressure

    Hello there :) First I'm sorry for my English it might be kinda bad ! I Have a little question about Weight and Pressure, Hope this is the right place. Here in this image we have 3 samples, A, B and C. They are 3 different types of shapes fulled with a liquid (let's say water) Talking...
  18. T

    Proving that apparent weight is 5 times actual weight (no numbers)

    Homework Statement Without numbers, identify how you could find the apparent weight of motorcycle to be 5 times that of the actual weight. The motorcycle is going up a loop the loop with a velocity of v. Homework Equations Fnet = mv^2/r Fg = mg The Attempt at a Solution Fnet = mv^2/r...
  19. Gh778

    Weight of the support of a pendulum with initial speed

    Hi, I'm interresting about the weight of the support of the pendulum with an initial speed. It is the http://en.wikipedia.org/wiki/Pendulum but with an initial speed. The mass come at top with straight initial speed and after turn around the pendulum. I attempt to have the weight of the...
  20. T

    Pump water weight upward pressure needed

    I'm designing a bucket pump for a water well I'll be attaching a pumpjack to. I'm just a regular shop guy so I was kind of stumped on a question of how much upward pressure will be required to move the water up the drop pipe. If the pump cylinder is the same diameter of the drop pipe I figure...
  21. P

    Weight in an Elevator and Normal Force

    Homework Statement A person who normally weighs 200 lbs is standing on a scale inside of an elevator. The elevator is moving downwards at a constant speed of 7.0 m/s and then begins to slow down at a rate of 4.9 m/s^2. Before the elevator begins to decelerate, the reading of the scale is...
  22. M

    Why Does Acceleration Down Make an Object Weigh Less?

    I don't understand conceptually how something accelerating down weighs less. For example, the elevator example of course if you have something with a string and a weight and the acceleration of the elevator increases upward as positive, you get T - mg - ma = 0 and for acceleration down, you...
  23. K

    How do I calculate mass when I have the height and weight?

    I need to calculate a lions mass and all i know is the height and mass!
  24. N

    Whether sum of weight of proton and neutron is equal to atomic mass?

    Dear friend, I am getting confused in this question;what i learned till now is that number of proton+number of neutron=atomic mass. But while searching the net i got this equation atomic mass = mass a x fract a + mass b x fract b. can anyone tell me which is the correct (not approximate)...
  25. S

    Weight of N 3-Dimensional Quantum Harmonic Oscillators

    Hey guys, The question gives us N 3-Dimensional Quantum Harmonic Oscillators with : E=ƩE(i)=Ʃ(n(i)+0.5)(h-bar)w Where h-bar is the reduced Plancks constant, w is the angular frequency, and the sum takes place over i=1 to i=3N, and (i) is subscript! Now I believe the microstates of this...
  26. AakashPandita

    Weight of a body in a water column

    The weight of a body is less when it is submerged in water, due to the upthrust. But the weight of the water column above the body can be far more than the upthrust(weight of the displaced water). So is it not that the weight of a body can increase when it is submerged in water?
  27. N

    Components of Weight on an Inclined Plane

    Hey, Imagine a frictionless inclined plane situation where the ramp goes up and to the right. If we put an object on it with any mass m, would it be fair to say that both of the components of the weight are negative? My reasoning is that the x component causes acceleration to the left and the...
  28. E

    Stoichiometric reactions with weight percent

    i can't figure out how to calculate this. Please help! How many grams of 6.000 wt% aqueous HF are required to provide a 50% excess to react with 10.0 mL of 0.0236 M Th4+ by the following reaction? Th(4+) + 4F - → ThF4 (s) I found the molarity for Th(4+) to be 2.36*10^-4.. I'm not really...
  29. MathWarrior

    Weight attached to a spring general question?

    I was wondering, in my class we have been dealing with a lot of equations related to some weight attached to a spring which is attached to a fixed point and has some force being applied to it or something like that. Where exactly is such a thing encountered in real life?
  30. zoobyshoe

    Distribution of Weight on Two Supports

    An oblong weight of uniform shape and density is supported horizontally on two supports. The placement of the two supports can be shifted. What is the best way to determine what percentage of the weight is born by each support given any possible arrangement of the supports?
  31. X

    Weight required to balance a boom stand?

    Hi! I am trying to build a stand with a boom arm for my acting classes and I need to find the weight required to balance it. The problem is that it looks like I was more like a swan when I was swimming in the physics lessons ... no a lot of drops stayed on my plumage ... :) Help...
  32. J

    Given tension and acceleration determine max weight

    Homework Statement A fisherman in a boat is using a "10- test" fishing line. This means that the line can exert a force of 45 without breaking (1lb = 4.45N). If he accelerates the fish upward at 1.8m/s/s , what maximum weight fish can he land, in Newtons? Homework Equations F=ma The...
  33. C

    Help needed, converting weight to a falling force.

    Hey all, Just a quick overview of myself, I have recently started rock climbing (6 month) and I'm finding myself becoming more curious about the technical equipment involved. I'm finding it hard to word the questions I'm trying to find the answers too. So I'm going to try and I'm...
  34. O

    Does pressure affect the weight of water?

    I have something I need cleared up and looking for some calculation help. I know that water changes density with temperature but does it change due to lack of gravity when the moon is close? So to clear things up I guess I need to know what and how thoes changes will affect the weight of water...
  35. mcknia07

    Can MyFitnessPal and Zumba Help Me Lose Weight?

    I'm using the app on my iPod that's for myfitnesspal. Great app to help count calories. Also, I'm doing the Zumba exercise program to help with the weight loss/tone up. Any opinions on all of this??
  36. A

    How to calculate the ratio of weight?

    Homework Statement Two body move apart by force. Frictional forces are considering. How to calculate the ratio of weight? m1<m2 Ft1=k*g*m1 Ft2=k*g*m2 Homework Equations v1(t1)=\frac{F_{t1}-F}{m_{1}}*t_{1} x1(t1)=\frac{F_{t1}-F}{m_{1}}*\frac{t^{2}_{1}}{2}...
  37. M

    What is the Apparent Weight on a Ferris Wheel?

    Homework Statement As you ride on a ferris wheel, your apparent weight is different at the top and bottom. Calculate your apparent weight at the top and bottom of a Ferris wheel, given that the radius of the wheel is 7.2 meters, it completes one revolution every 28 seconds, and your mass is...
  38. N

    Gravity and Weight: Newton's Second Law

    Hey, About Newton's Second Law. To compute our weight on Earth using standard g, we use F=ma replacing F and a with W and g (or -g), respectively. So then from this, I gather that weight is a consequence of gravitational acceleration (and mass). So then, it is appropriate to say that our...
  39. S

    Finding tension and acceleration in a 3 weight, 3 pulley system

    Homework Statement This is a "DOE" (Design of Experiment) problem. Basically, the construction is fairly simple. 3 pulleys, 2 on either side, and a free pulley with a weight suspended on it in the middle. Picture is available (don't mind my crappy paint skills, rope lengths are all...
  40. T

    Calculating Density of Gas from Combusted Solid w/ Known Wt, Pres, Vol

    Hello, Thank you all for the help here. Here we go, I have a known solid weight start of the propellent. I know the PSI of a known volume chamber(After combustion) and Temperature, can I find density? So example Bullseye powder has a load of 0.336954332 grams (5.2 grains) The volume...
  41. V

    What is the approximate weight of a 20.kg rock

    Since it has a decimal it would be 20kg * 9.8m/s which equals 196kg m/s^2 = 196N But the decimal means i have to round two sig figs, which would make it 200N? A very simple problem, I really don't know why I'm asking it.
  42. A

    What weight does our weighing machine show?Is it the mass or weight(mg)?

    What weight does our weighing machine show?Is it the mass or weight(mg)?
  43. B

    Max weight that anyone can lift using over head pulley.

    Can a man whose weight is 50KG (but powerful arms) lift another man with 70 KG weight using an overhead pulley. I guess no since the light man is not clamped to the groud, his arm strength will not bear any significance and he can lift only the wieght(on other side of the pulley) equal to his...
  44. R

    How Do You Calculate Weight Percent Concentration of KCl in Water?

    Homework Statement What is the weight percent concentration of a saline solution prepared by dissolving 2.440 mole of KCl in 10 L of water? Homework Equations The Attempt at a Solution
  45. F

    Buoyancy & Weight: Does Ice Float?

    This is more of a conceptional question. Let's say you have 1L of water in a bucket on a weighing scale, which currently reads 50N. If a couple of ice cubes were added, would the weighing scale read 50N + weight of 2 ice cubes? Side-Notes: density of the ice < density of water ice...
  46. L

    What is the Average Monthly Weight Gain for a Baby Over a Specific Time Period?

    Homework Statement The weight of a baby measured over an 11-month period is given in the weight chart below for this problem. Weight (lb) Age (months) 6.6 0 (birth) 7.4 1.0 9.6 2.0 11.2 3.0 12.0 4.0 13.6 5.0...
  47. P

    Calculating time from 0-75meter with power and weight.

    Anyone who knows how to calculate the time a formel car will take from 0-75meter. The specs are 110HP and weight is 300kg. I've tried to calculate this without any luck..
  48. W

    Force, mass versus resistance to move a weight

    I have my own theory on this, but first would like to ask the forum. And the members answering on my other thread, this question is separate but needs to be answered first. Also I have started answering that one. If use lift 80% of your 1RM, repetition maximum, why is it easier on a barbell...
  49. V

    Automotive What Is the Mass of an Average Car and Engine?

    Hi I just wanted to know what is the mass (in kilogram) of an average car and the mass of an average engine. This is for my project and I want to know their masses to make a scaled model of a car for my experiment.
  50. W

    How much do you weight in an elevator?

    Does your weight change in elevator? I have recently found an answer to this question but I can't understand it completely. So, here is the answer : No, your weight is unchanged. To provide the acceleration upwards, the floor or scale must exert on your feet an upward force that is greater in...
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