In science and engineering, the weight of an object is the force acting on the object due to gravity.Some standard textbooks define weight as a vector quantity, the gravitational force acting on the object. Others define weight as a scalar quantity, the magnitude of the gravitational force. Yet others define it as the magnitude of the reaction force exerted on a body by mechanisms that counteract the effects of gravity: the weight is the quantity that is measured by, for example, a spring scale. Thus, in a state of free fall, the weight would be zero. In this sense of weight, terrestrial objects can be weightless: ignoring air resistance, the famous apple falling from the tree, on its way to meet the ground near Isaac Newton, would be weightless.
The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, and about one-sixth as much on the Moon. Although weight and mass are scientifically distinct quantities, the terms are often confused with each other in everyday use (i.e. comparing and converting force weight in pounds to mass in kilograms and vice versa).Further complications in elucidating the various concepts of weight have to do with the theory of relativity according to which gravity is modeled as a consequence of the curvature of spacetime. In the teaching community, a considerable debate has existed for over half a century on how to define weight for their students. The current situation is that a multiple set of concepts co-exist and find use in their various contexts.
Hi, I am trying to understand how camera jibs work.
They seem to be able to remain at whatever angle despite being balanced. The counter weight is static and does not move, yet the jib does not remain level nor does lift or drops. I have spoken to the operators and they mention they don't use...
Where
##:## really means normal ordered, in the sense that ##:A(w)B(z): = \lim_{w \to z} \left ( A(w)B(z) - \langle A(w)B(z) \rangle \right )##
##\partial X(z) = \frac{\partial X(z)}{\partial z}##
How do we go form the first line to the second one?? I am not understanding it!
it seems to me...
TL;DR Summary: Used M1V1=M2V2 but am unsure if formula applies
I feel like I could use M1V1=M2V2 but the 18% by weight ammonium hydroxide is confusing me so much.
Density of ammonium hydroxide 18% is 0.926 g/cm3
18%V1=16mg/L*200L
(18mg ammonium/100 mg of total solution) * V1 = 3,200mg...
What is and how is the estimation of the ideal weight or force to push (bit being in) a driller down when drilling (stainless) steel to bore 3-9 mm hole?
I have a VERTICAL standing square tube 1.25" x 1.25" x 1/16" thick.
Length/Height = 79"
Material = steel
How do you determine its max load capacity for this tube when mounted vertically?
I plan to use 18 of these vertical posts, evenly spaced, creating an 83" x 131" rectangular structure.
They...
I have solved the question in the following way:
The downward force is equal to the upward force. the upward force is equal to the weight of water displaced. If we find the weight of the water displaced then we will know the upward force. And since upward force is equal to downward force, we...
So i found this on a journal, and im wondering what is n and how can i calculate the weight percentage ratio between the PEO and LiClO4. Here is the instruction.
To prepare PEO-LiClO4-Al2O3 PE samples, predetermined amounts of LiClO4 (such that oxygen to lithium ion ratio is n:1) and Al2O3 (as...
This is usual induced drag diagram.
I have 2 questions:
From Kutta–Joukowski theorem Fr is always perpendicular to effective airflow.
1. Does it mean for case without effective airflow(zero induced downward velocity), Fr is perpendicular to freestream airflow,so drag is zero?
When effective...
I am a bit overwhelmed with your forum site. I was not sure where to post my question...Here goes-
Full details…I have an e-bike. It weighs about 55 pounds. I have ridden it for the last year with a canvas bag attached to the rear flat book carrier. The canvas bag measures 19” long, 9” tall and...
It's a homework question, but I feel like it fits better in this forum. The solution fails to convince me because C_D and C_L can be both written in terms of weight:
$$C_L=\frac{2W}{\rho v^2 S}$$
$$C_D=C_{D0}+k_1 C_L(W)+K_2 C_L(W)^2$$
Question:
Solution:
Any insight will be appreciated.
When car drive uphill, gravity/weight has drag component, that is reason why you must add more throttle compare to ligther car at same constant speed uphill. So logicaly car increase fuel consumption.
But if you drive downhill, gravity/weight has thrust component, so your top speed("terminal...
Hello All,
I know there are rules of thumb and thread engagement calculators online but I am trying to find mathematically what the minimum number of threads acceptable would be.
I currently have an eyebolt that will be torqued to a specific value. This eyebolt setup will then need to lift a...
Hello
The formula Mgh is commonly accepted as the work done by raising a mass by a distance h, where M is defined as the mass of the object raised.
However, is this really the mass, or the weight, simply obtained by weighing the object? If it's the weight, then doesn't the equation...
Hello there, I have tried the problem but don't get a different of 6g's as I am supposed to. I am not sure whether I interpreted the problem in the correct way, but I would love some feedback/hints on what went wrong in my solution, thanks in advance.
Solution:
SITUATION DRAWINGS + FBDS
so...
Hello,
I’m not sure if the proper term is shock load. If a person is using a device and rope to lower themselves from a high point and they’re descending fast and then suddenly stop does that create a shock load? The device attaches to the rope and when a person squeezes the device it allows...
How much Weight (W) is required to keep a weight hanging straight down when the torque is known on a rotating shaft? Please see attached image. Assume a lever weight of zero to keep it simple.
Hi,
I want to know how to calculate the effective weight if i have an object with the weight 'X' that is mounted from the side to a wall, and what happens with the weight if i increase the distance between the wall and the object.
The reason i ask is as follows for the interested.
I have a...
Good afternoon everyone,
I have a question on Newton's 2nd Law regarding objects on a generic incline. Take for example, a car on a banked curve:
Here in the picture I've provided, you can see that the normal force has been decomposed into the x and y components via sine and cosine of the...
I was watching one of Walter Lewin's lectures, he gave an example of a scale placed at your feet in a moving platform, apparently your weight changes when the moving platform accelerates downward, my question is if my reasoning is correct. I'm wondering why your feet stay in contact with the...
Hi all. I'm designing a custom spare wheel carrier for my 4wd and currently seeking knowledge on which bearings to use, so I need to work out what force on the bearings will be when it's open (closed will be locked and fully supported!)
The example image is simplified for calculation. Close...
Each weight: 2 Kg
Hello All, I'm trying to understand an "apparent weight" problem and check my answer. Please use the picture attached.
A weightless beam is at first resting over my palm, it has one 2 kg weight on each end of it. It is suspended to the ceiling by a rubber band. I drop it and...
Tank volume is 768l plus the tank and rock to go inside
2000m x 640mm wide x 600mm high
Stand is made of 35mm square x 3mm wall thickness.
Tank width is the same as the steel frame, notice the tank is not over the end legs.
Wooden top is 50mm thick pined and glued planks...
4x top supports...
Hi,
I was wondering, what is my apparent weight in water?
For example, when I tiptoe on land, my calf muscles are pretty much lifting all my body weight.
But if I were to tiptoe with just my head out of the water, how much weight would my calves be lifting?
And as I move to shallower water, how...
Since we are dealing with an ideal rope, we have that ##T_1=T_2=T_3=F and T_2+T_3=2F=(m+m_p)g\Leftrightarrow F=\frac{m+m_p}{2}g.##
##T_4=3F+(m+m_p+M_p)g=\frac{3}{2}(m+m_p)g+(m+m_p+M_p)g=(\frac{5}{2}m+\frac{5}{2}m_p+M_p)g## and ##T_5=mg-2F.##
Is this correct? If not, I woould appreciate a brief...
https://www.feynmanlectures.caltech.edu/I_09.html
“Weight and inertia are proportional, and on the earth’s surface are often taken to be numerically equal, which causes a certain confusion to the student. On Mars, weights would be different but the amount of force needed to overcome inertia...
Can you pull down/hold more weight than your body using your muscles?
Imagine a 1 to 1. One side is suspended 190 pounds, the other is me, 175 pounds. Can i, using my muscles and standing on the ground, hold that suspended weight off the ground?
I understand if i lock out my arms and...
For practice I did the following problem:
Solving this problem mechanically was simple enough using the following force diagrams:
Then
$$F_{net_M} = T - Mg = 0$$
Due to the stationary condition
$$T = mg$$
and
$$F_{net_m} = T = ma_c$$
$$T = ma_c$$
Because centripedal acceleration is...
Hello,
I am interested in making an RC plane as illustrated. Some questions:
1. Given that the build material of the plane will be 3d printed out of PLA and I want the wingspan to be between 1.2m - 1.35m ideally. How can I calculate the minimum wingspan/wing shape/wing area to carry a payload...
I found the density of carbon and iron:
ρ_fe=7.87 g/〖cm〗^3
ρ_c=2.26 g/〖cm〗^3
Using equation 2:
atom density of iron and carbon
N_fe = 8.48e22 cm^-3
N_c = 1.13e23 cm^-3
Using equation 1:
macroscopic scatter and absorption cross sections of iron and carbon
Σ_a,fe = .217 cm^-1...
how do I calculate how much force is needed to lift a horizontal metal tube to a vertical position. The metal tube is 25 feet long, weighs 300lb and and pivots 5 foot from the bottom. I will be using a hand winch and the cable attaches at the bottom of the 5 foot end of the tube.
A man and a boy hold opposite ends of 8m long pole which is horizontal. A mass of 200 kg is tied to the pole. If the man is to support four times as much weight as the boy where along the pole must the weight be tied?
Can someone please help
The force exerted downwards on the scale by the chain when it is kept on it would be
Fg= Mg
=λLg where λ is the linear mass density
However when the chain is dropped onto the scale it exerts an additional force due to its change in momentum
The force exerted by each part of the chain would...
Hello everyone. I'm building myself a half-rack for weight lifting that included 2 overhung support beams above from which to hang a safety strap incase of a failed lift. They are made from 2x3x.125 steel tube (they're Oriented with the 3" vertically). The tube are overhung by 21". How much...
Hi everyone! I regularly use the forum to learn but never registered to post anything, as I have nothing to teach really…
But today I have a question regarding the law of conservation of energy that I can’t find the answer to, and maybe someone will help me understand:
(I’ve attached a drawing)...
I 'get' how the gyroscope works, but I only understand it mathematically. I understand that because Torque = r x F, so the direction of the torque is such that it can change the direction of the Angular momentum, resulting in the gyroscope precessing.
However, I just cannot visualise how this...
Hi,
This has long been in my head, I've seen it work out in reality, but I have no idea about the forces involved in this. As I don't have an engineering degree or mathematical knowledge in automotive engineering, I've come here for help. Sorry if I've used some terms where they do not fit, as...
I read about a proposal for storing potential energy by hoisting heavy weights that can be dropped when needed to generate electric power. So using the numbers from a hydraulic turbine from Hoover dam, how heavy would a hanging weight have to be to generate 178,000 horsepower as it descended...
I’m trying to calculate the weight I have to support at one end of a pipe with flowing water. So suppose you had a water pipe that extended from the ground upwards some distance away both horizontally and vertically, i.e., at an angle. Normally, you don’t have to worry about this issue because...
Hi, I'm working on a project to see if deliveries, pick ups, or both combined are better for the environment / more energy efficient / more time efficient. For example, (a) everyone collecting from a farm by bike, (b) vans bringing to supermarkets and then people collecting from supermarkets, or...
I am interested to compare two scenarios relating to grip strength and how much horizontal pressure will be required to hold the weight.
Scenario 1: You have a 20kg weight plate in one piece. You hold the plate between your fingers.
Scenario 2: You are holding a small 2X4 block of wood with a...
a. To find the speed, I need to find the height where the cords first become loose, which is when the cord is 25 m long.
$$h=30-\sqrt{25^2 - 5^2}$$
But the teacher's working is ##h=30-\sqrt{25^2 - 4^2}##
How to get 4?
b. My idea is to use Newton's 2nd law so I draw free body diagram of the...
Hi guys,
I don't have much knowledge of physics sadly, and I want to build a machine that can spin a disk.
My question is - How can I know the weight I can spin on a motor?
I need to be able to spin around 5-6kg, for 350 RPM, and I'm not sure I'm aiming for the correct motor.
I'm thinking of...
Hello,
I need to scale down a human model by 1:20
i.e,
i need a human model of 9 cm height scaled down.
Help me calculate the weight of the 9 cm scaled down human model.
Regards,
Viky
Could I please ask for help with the following question:
A uniform lamina of weight W is in the shape of a triangle ABC with AB = AC = 2a and the angle BAC equal to 2ᾳ. The side AB is fixed along a diameter of a uniform solid hemisphere of radius a. The plane of the lamina being perpendicular...
What does it mean that the relationship between material mass and weight is constant and proportional?
Hi! Yes, another question... I have many doubts. :)
I hope someone can help me with this apparently very basic doubt, but I feel like a stupid monkey trying to join two sticks to reach bananas...
During the day, I am between sun and earth. During the night, I am behind the Earth if I'm looking from the sun.
So its
Day: sun-me-earth
night: sun-earth-me
So the forces of gravity from sun and Earth add during the night, but during the day, the sun attracts me away from the earth...