What is Hooke's law: Definition and 260 Discussions
Hooke's law is a law of physics that states that the force (F) needed to extend or compress a spring by some distance (x) scales linearly with respect to that distance—that is, Fs = kx, where k is a constant factor characteristic of the spring (i.e., its stiffness), and x is small compared to the total possible deformation of the spring. The law is named after 17th-century British physicist Robert Hooke. He first stated the law in 1676 as a Latin anagram. He published the solution of his anagram in 1678 as: ut tensio, sic vis ("as the extension, so the force" or "the extension is proportional to the force"). Hooke states in the 1678 work that he was aware of the law since 1660.
Hooke's equation holds (to some extent) in many other situations where an elastic body is deformed, such as wind blowing on a tall building, and a musician plucking a string of a guitar. An elastic body or material for which this equation can be assumed is said to be linear-elastic or Hookean.
Hooke's law is only a first-order linear approximation to the real response of springs and other elastic bodies to applied forces. It must eventually fail once the forces exceed some limit, since no material can be compressed beyond a certain minimum size, or stretched beyond a maximum size, without some permanent deformation or change of state. Many materials will noticeably deviate from Hooke's law well before those elastic limits are reached.
On the other hand, Hooke's law is an accurate approximation for most solid bodies, as long as the forces and deformations are small enough. For this reason, Hooke's law is extensively used in all branches of science and engineering, and is the foundation of many disciplines such as seismology, molecular mechanics and acoustics. It is also the fundamental principle behind the spring scale, the manometer, the galvanometer, and the balance wheel of the mechanical clock.
The modern theory of elasticity generalizes Hooke's law to say that the strain (deformation) of an elastic object or material is proportional to the stress applied to it. However, since general stresses and strains may have multiple independent components, the "proportionality factor" may no longer be just a single real number, but rather a linear map (a tensor) that can be represented by a matrix of real numbers.
In this general form, Hooke's law makes it possible to deduce the relation between strain and stress for complex objects in terms of intrinsic properties of the materials it is made of. For example, one can deduce that a homogeneous rod with uniform cross section will behave like a simple spring when stretched, with a stiffness k directly proportional to its cross-section area and inversely proportional to its length.
Homework Statement
A 70 kg bungee jumper leaps off a bridge. She is tied to a 12 m long bungee cord and falls a total of 31 m. Calculate:
a) the spring constant of the bungee
b) the maximum acceleration experience by the jumper
Homework Equations
F = kx
Eg = Ee
where g is...
The problem:
See attachment for figure.
(1) A rope with a spring constant k is stretched by a force F.The length of the rope is l (including the deformation).
(2) A force mg is then applied at l/2 on the rope. This results in a height difference between the highest (and unchanged point) and...
does plywood follow hooke's law? is the young's modulus for plywood constant across the beam? :) and if u have any other hints with deam deflection I am willing to have them :P
thanks!
A 0.2 kg block of wood is attached to a spring with a spring constant k = 25 N/m. The block is initially at rest and the spring is at its equilibrium length aligned along the x-axis. A dart of mass 0.05 kg is thrown at a block of wood, undergoes an inelastic collision and sticks into the...
How to calculate the elongation when we know we all other parameters?
Two sides of a rod is pulled by two forces of F Newtons in opposite directions. What should we consider F or 2F in the equation? I used 2F and got wrong answer as per the book. But, if it is true, why should be use F...
I need to figure out an equation that shows the relationship between the force constants of two springs that are connected together.
I know that the 1/ktot = 1/k1 + 1/k2
but I have to shows all the steps to obtain this equation...
I know that
F = k1x1 = k2x2 = k(x1 + x2)
I tried...
Hello all, newbie here
Google led me to this thread:
https://www.physicsforums.com/showthread.php?t=70094"
which happens to be basically my question. I am doing an investigation on Hooke's Law for my VCE Physics class (Australian year 12, senior school).
Thanks to wikipedia's derivation...
Homework Statement
*1* The Gibbs function G(T; P) of a certain gas is:
G = nRT ln P + A + BP + (1/2)*CP^2 + (1/3)DP^3
where A, B, C and D are constants. Find the equation of state of the gas.Homework Equations
G = nRT ln P + A + BP + (1/2)*CP^2 + (1/3)*DP^3
The Attempt at a Solution
I think...
Homework Statement
Obeying hooke's law. A hot air balloon is 65.0m from the ground. The bungee jumper wants to jump with a uniform elastic cord up to 10m above the ground. During a preliminary test, the cord at rest was 5.0m and when he got on it stretched 1.50m. a) What length of cord should...
A spring with spring constant k=340 N/m is used to weigh a 6.7 KG fish. How does the spring stretch?
I used Hooke's law (F=-Kx), but ended up having a negtive distance x=-0.2m. Is this expected? in the problem they say the spring stretches...this is confusing me...thank you for your help guys...
One end of a horizontal spring (k = 333 N/m) is attached to a 3.12 kg box, and the other end to a fixed, vertical wall. (A picture of this situation can be found in Fig 4-10 on page 102 of your textbook.)
a) Find the magnitude of the force needed to move the mass so the spring is stretched...
[SOLVED] Springs and Hooke's law
Homework Statement
An unstretched spring has a force constant of 1200 N/m. How large a force and how much work are required to stretch the spring by 1.00 m from its unstretched length?
Homework Equations
F= -k*s
W= F * s
The Attempt at a Solution...
[SOLVED] Spring Hooke's law
Homework Statement
The innerspring mattress is held up by 23 vertical springs, each having a spring constant of 5000N/m. A 44 kg person jumps from a 1.94m platform onto the innersprings. Assume the springs were initially unstretched and that they stretch equally...
[SOLVED] Hooke's Law: Two springs in series
can someone explain and prove to me why the equation for two springs in series is
K= [(1/k1)+(1/k2)]^-1 ?
this is how far i got
F= -k ∆x
F= -k (x1+x2)
Homework Statement
All right I have a graph of a spring being pushed by a person's hand. the hand is exerting force upon a force sensor attached to the spring. (So the force sensor can be measuring the force of the person's hand or the force of the spring). The questions says that the graph...
Homework Statement
How would F(g) and (delta) X change if the Spring experiment was done on the moon where the gravitational acceleration is six times smaller than on earth?
Homework Equations
F(g) = (delta) mg
F(s) = k(delta) X
The Attempt at a Solution
I would think that F(g)...
Homework Statement
Four people, each with mass of 71.3 kg, are in a car with a mass of 1130 kg. An earthquake strikes. The vertical oscillations of the ground surface make the car bounce up and down on its suspension springs, but the driver manages to pull off the road and stop. When the...
Homework Statement
A daredevil plans to bungee jump from a balloon 65.0 m above a carnival midway. He will use a uniform elastic cord, tied to a harness around his body, to stop his fall at a point 10.0 m above the ground. Model his body as a particle and the cord as having negligible mass and...
Homework Statement
During spring semester at MIT, residents of the parallel buildings of the East Campus dorms battle one another with large catapults that are made with surgical hose mounted on a window frame. A balloon filled with dyed water is placed in a pouch attached to the hose, which...
Help me??
I need to find three different names for the constant between length and force in hooke's law. I also need to find out why, when rubber bands are stretched by force, at a certain force, they actually get shorter. can anyone help?
A spring pushed or pulled with a force F is elongated by x according to Hooke's law:
F = -k . x
where k is a constant of the spring.
Does the k constant changes when seen from a reference frame at rest ?
The spring is moving.
This comes from...
Homework Statement
It takes 2.11 J of work to stretch a Hooke's law spring 6.08 cm from its unstressed length. How much the extra work is required to stretch it an additional 6.93 cm?
Homework Equations
F = -kx, W = Fd
The Attempt at a Solution
I first solved for Force by...
Iv done an experiment with a spring wher you add mass and record the new length. From a table of these rusults iv plotted length (m) against mass (kg), like so
Now i have to calculate the stiffness, k, from this graph with the equation:
mg = k (l - lo)
so just to varify that what iv...
Homework Statement
This isn't acctually a problem but I really don't know what to do. I was doing a simple activity about Hooke's Law during class today where I have to set up a apparatus and measure the extension of spring when when we put differnt masses on it. I didn't do it properly so I...
Homework Statement
I am doing a lab experiment and the objective is to find the efficiency of an elastic band.
Distance to ceiling=2.9m
Mass of elastic band= 1.85g
Force 2.6N (found using Newton meter)
Extension: 6.4cm
Homework Equations
Well I am not looking for a solution, I...
A piece of fabric obeys Hooke's Law - force is proportional to extension - when stretched in one direction.Is it possible for the fabric to continue to obey Hooke's Law if it is simultaneously stretched in another direction at right angles to the first direction?
Homework Statement
These relate to a Hooke's law lab involving springs.
What are the differences between ideal springs and real springs.
Also, does anyone know why applied force is plotted on the vertical axis of a graph while x (change in displacement from equilibrium) is plotted on...
Homework Statement
-How does the total force constant of two springs hung linearly compare with the individual force constants of springs.
-Predict the equation that relates the total force constant, ktotal, to the individual force constants, k1 and k2, of two springs joined together...
Ok, here is a physics problem that I cannot figure out for the life of me. I feel as though I can't solve it without knowing either the mass of the bungee jumper or the spring constant for the cord. Is there a way to get it somehow? Perhaps an important number is missing? I would appreciate any...
Hey, I am confused about the Hooke's Law about the spring. If I am holding a spring vertically and hanging weights on the bottom of the spring so that my spring will be stretched longer, do I get a positive delta x? The equation of Hooke's Law is F = kx. If I do get a positive delta x, do I get...
hooke's law says the spring force = -kx
but the work done in stretching a spring = 1/2 kx^2
isnt work = Fd?
so using W=Fd and F=-kx (hooke's law) shouldn't the work come out to:
W = -kx^2? (arent d and x the same? both are distance stretched)
where does the 1/2 come from in the...
When a 4.00 kg object is hung vertically on a certain light spring that obeys Hooke's law, the spring stretches 2.5 cm.
(a) If the object is replaced with one of mass 1.45 kg, how far will the spring stretch?
F=ma
-ma=-kx
-(4)(9.8)=-k(0.025)
k=1568
-(1.5)(9.8)= -1568x
x=0.00938m
I...
When a 4.00 kg object is hung vertically on a certain light spring that obeys Hooke's law, the spring stretches 2.50 cm. (a)If the object is replaced with one of mass 1.50 kg, how far will the spring stretch?
b) How much work must an external agent do (i.e. a force coming from the...
I think I am getting some concepts confused, so i need help clarifying the answers to the following questions:
1. can you use a rubber band instead of a steel spring in a scale to measure weight?
- I said no, because it would break
2. Should the wires supporting a suspension bridge be elastic...
Okay, I'm having a debate with my teacher. He's saying I'm wrong but I still think I'm right. The question is:
What should be the spring constant, k, of a spring designed to bring a 1200kg car to rest from a speed of 100km/h so that the occupants undergo a maximum acceleration of 5.0g?
He...
I'm having some trouble with the following question:
http://www.mattmaly.com/spring.jpg
Obviously I know to use Hooke's equation somewhere in this problem: F = -kx
In the above equation, F = the force, caused by gravity, of the board pulling the spring horizontally, and k = 176 N/m as...
Hey there everyone. First post, so... yeah.
Anywho, I got a few questions on Hooke's law as a homework assignment. But the last one is giving me some trouble. I'll tell what I've done so far that leads up to the problem.
The first question asks to calculate the work done given a Graphical...
I need to calculate a spring constant using measurements from a Hooke's Law Apparatus, a spring, and some weights. Frankly, I have no idea what I need to do. I've taken the measure ments, and discovered the formula F=kx, where F=Force, k=spring constant, and x=the compressed distance.
I'm not...
Hi again, all. I thought of another question that I need help with. Again I have the answer but I'm not sure how they got to it. The question is:
A 1.6kg block is supported on a horizontal surface. The block is attached to a sping with k = 1000 N/m. The block compresses the spring x = 0.02 m...
Hello,
I found one of my this homework question difficult and was wondering if anyone could please help me.
A 180g trolley is placed on frictionless air track. One end of the trolley is attached to a spring of spring constant 50 N/m. The trolley is pushed against a fixed support so that...
hmm ok, i was watching the MIT opencourseware video on oscillations and there was a part where it was mentioned that,
the diff. eq. x''+ \frac {k}{m} x = 0 has solution x= x_0 cos (\omega t + \phi) if and only if \omega= \sqrt{\frac {k}{m}}
how do i show that omega is the sqaureoot of...
A compressed spring that obeys Hooke's law has a potential energy of 18 J . If the spring constant of the spring is 400 N/m, find the distance by which the sping is compressed.
Please correct me if I am wrong, I'm not sure how find the distace.
My work: k 400 N/m x=18J = 400 N/m/18...
I don't know anything about diff eq but:
F = ma = -kx(t)
a = \frac{d^2(x)}{dt^2}
-kx(t) = m\frac{d^2(x)}{dt^2}
So we need a function whos second derivative is the same as the function itself.
I know hooke's law says the function is cos(\omega t) but I don't see why e^x...
Morning peoples,
I have a query about Hooke's Law. :confused: I have a problem which asks me to calculate the spring constant (k). I know how to do it, but my question is when I use the formula mg/x can mass be in Newtons or does it have to be in kg?
Looking forward to your answers...
A 450kg bumper car, with a spring which have a spring constant of 3x10^7 N/m collides at a speed of 2m/s with a solid wall. It gives a maximum compression of 7.7mm. At what speed will the car rebound of the wall?
I am having trouble with this one... I don't know how to go about solving the...
A spring with k=45 N/m is .35m when pulled
down with a 1.0 kg mass, what is the length of the
spring when the mass is taken off? The answer in the
back of the book is .13m (13 cm), I can't for the life...
We did an experiment with a vertical spring-mass system. Here is an example of data collected:
Mass------------T (period)
200 g-----------.3 s
400g------------.5 s
My question is why does the period increase as the mass increases?
I know that the amp. and T are independent of each...
I have found a website which claims that rubber bands obey a force law
F=-kT(x-\frac{1}{x^2})
x=\frac{L}{L_0}
While this is similar to Hooke's Law in the sense that it *almost* approaches it for large values of x, it is also quite different. Can anyone confirm or deny the formula's...
allright, here is something i haven't been able to understand with just hooke's law
if i have an object traveling at velocity v, let's say, 4m/s , and hits a spring at, i don't know, k=2? so then we know how far the spring compresses and all because you just need to set the work done and...