Second law Definition and 491 Threads

Homework Statement A pulley, with a rotational inertia of 1.0 x 10^-3 kg*m^2 about its axle and a radius of 10 cm, is acted on tangentially at its rim. the force magnitude varies in time as F=0.50t + 0.30t^2, with F in Newtons and t in seconds. The pulley is initially at rest . At t=3.0 s...

A steam turbine in a power plant accepts 4500 kg/hr of steam at 60 bar and 500°C and exhausts steam at 10 bar. Heat transfer to the surroundings (Tsurr = 300K) at a rate of 70 kW. (a) What condition needs to be satisfied for the turbine to generate the maximum possible power? (2 marks) (b)...

Lubos has a posting today about how Lorentz violating theories of quantum gravity seem to imply violations to the second law of thermodynamics: http://motls.blogspot.com/2008/04/lorentz-violation-makes-perpetuum.html I don't quite understand the arguments, but e states that ``the second...

An important issue here. In 2001 Bojowald discovered that quantizing the basic (Friedmann) model of cosmology got rid of the classical singularity and typically replaced it by a bounce. A prior contracting phase leads up to the start of expansion. In the years that followed Penrose raised the...

[SOLVED] Newtons Second Law Homework Statement On a force/mass vs acceleration graph where force/mass is horizontal, what does the slope represent? Homework Equations The Attempt at a Solution My calclations: ex. (2m/s^2 - 1m/s^2)/(3 N/kg - 1N/kg) =.5 (m/s^2)/(N/kg)...

[SOLVED] HW: Newton's Second Law and Angles Homework Statement The system shown in the figure can be used to measure the acceleration of the system. An observer riding on the platform measures the angle (theta) that the thread supporting the light all makes with the vertical. There is no...

The Problem: A 4 kg dog stands on a 16 kg flatboat at distance 12 m from the shore. The dog walks 5 m along the boat toward the shore and then stops. Assuming no friction between the boat and the water, find how far the dog is then from the shore. The dog's displacement is towards the shore...

Homework Statement Two objects of unequal mass are hung vertically over a frictionless pulley of negigible mass. Determine vector a1, vector a2, and the tentions. m1<m2 Homework Equations ΣFy=t-m1g=m1ay ΣFy=m2g-T=m2ay -m1g+m2g=m1ay+m2ay ay=m2-m1/(m1+m2)g The Attempt at a...

Hi I am going through an extreme headache trying to udnerstand the carnot engine and the second law of thermodynamics. To prove that the carnot engine (refreigerator engine) is the most efficient, my text included a prototype engine with a carnot refrigetrator together. So, the author says...

An object (mass 10.0 kg) slides upward on a slippery vertical wall. A force F of 60 N acts at an angle of 60 degrees (the force is 60 degrees South of the x+ axis, it's shown in a picture) Determine the normal force exerted on the object by the wall. Next, determine the object's acceleration...

Graphs Of Acceleration And Force Hi! We did this lab...on Newton's Second Law. we are trying to prove the formula F=ma... Now i drew this graph of acceleration vs time and force vs time...they look similar..how can i interpretate them? someone help! MY lab is due tomorrow!

Homework Statement suspended a heavy weight from a light string and attach a similar string below it. if you pull on the lower string with a steadily increasing force, the upper string will break; if you pull the lower string with a jerk, the lower string will break. please explain to me...

Hi all, Having some trouble understanding/finding the derivation of Fick's second law of diffusion in cylindrical co-ordinates. I have attached the solution which describes the refilling of a laser cleaned spot via surface diffusion. So basically i would like to know the intermediate...

Hey all, I am new to Physics. Recently changed majors from technical writing to physics for the amount of interest I have in the subject. I have been doing ok but I missed a couple of questions on my last homework and I feel that I should have had somebody check my general solved statements...

can anyone proove "kelvin plank" statement of second law of thermodynamics or atleast show that it is always followed in any cyclic process...

Homework Statement A 800 g steel "cart" has a square steel rail running through the middle of it, touching the steel cart on all four sides of the rail. An elastic cord attached to the front of the cart and the "ceiling" of the apparatus creates a 45 degree angle from the horizontal axis in...

Homework Statement Open Question 3.bmp Homework Equations The Attempt at a Solution Open Answer 3.bmp Any help with this would be greatly appreciated

in the Newtons second law of motion we study "F=ma" letters having their usual meanings. so if any object say"A" comes in the way of a huge object "B", moving with a constant velocity; a=0, doesn't the object "a" feel any force upon him?

I am educated enough to know the Big Bang was not an explosion, but rather an expansion. However, does this not violate the Second Law of Thermodynamics? How can stars, galaxies, and planets develop and lose enthropy if the Second Law says that it should gain enthropy. Also, the universe was...

Homework Statement We have a rigid bar (length L) with an axis of rotation through the center of the bar. The bar is attached to a pulley with radius Rp at the axis of rotation. Two lead weights (mass M) can be screwed on the bar at equal distances R from the axis of the pulley. In each trial...

I already learned about Newton's Third Law but nowhere in my reference book can I find Newton's First and Second Law. Surely there must be the First and Second Law before the Third Law is taught. What is Newton's First and Second Law about ?

An applied force accelerates mass A at a rate of 6.0m/s^2. The same force applied to mass B accelerates the mass at a rate of 8.0m/s^2. If the same force were used to accelerate both masses together, what would be the resulting acceleration be?

Homework Statement For sport, a 12 kg armadillo runs onto a large pond of level, frictionless ice with an initial velocity of 5.0 m/s along the positive direction of an x-axis. Take its initial position on the ice as being the origin. It slips over the ice while being pushed by a wind with a...

You are pulling your little sister on her sled acroos an icy(frictionless) surface. When you exert a constant horizontal force of 110 N, the sled has an acceleration of 2.5 m/s^2. If the sled has a mass of 7 kg, what is the mass of your little sister? Heres how I attempted it: F=110N A=2.5...

A machine has an 760g steel shuttle that is pulled along a square steel rail by an elastic cord . The shuttle is released when the elastic cord has 16.0N tension at a 45º angle. What is the initial acceleration of the shuttle? Here is the only photo associated with this...

Homework Statement While two forces act on it, a particle is to move at the constant velocity v = (3 m/s)i - (4 m/s)j. One of the forces is F1 = (2N)i + (-6N)j. What is the other force? Homework Equations Fnet = ma The Attempt at a Solution Well, I'm really just wanting a...

Homework Statement After falling from rest at a height of 29.8 m, a 0.596 kg ball rebounds upward, reaching a height of 23.9 m. If the contact between ball and ground lasted 1.68 ms, what average force was exerted on the ball? Homework Equations The Attempt at a Solution so I...

Homework Statement A 3.00kg object is moving in a plane, with its x and y coordinates given by x=5(t^2)-1 and y = 3(t^3) + 2, where x and y are in meters and t is in seconds. Find the magnitude of the net force acting on this object at t=2.00s Homework Equations F = ma The Attempt...

Newtons second law problem, show all work including units Question: How much horizontal net force is required to accelerate a 1000 kg car at 2 m/s^2?I am not sure which formula to use in this equation

kirchhoff's second law...having exams soon, please help Homework Statement i got this circuit, in the attachment below. i was asked to find: (1) I1 and I2 (2) the voltmeter reading (the voltmeter has one terminal connected at the point between the 2 ohm resistor and the 12V battery, say...

I need to integrate \frac{mdv}{F(v)} = dt to show that t = m \int^{v}_ {vo} \frac{dv '}{F(v ')} Now, I now that velocity is the derivative of position, and the mass is constant, but how does one integrate F(v)? [Integrating is a weak spot for me] Thanks in advance!

Homework Statement F=ma can be written as F=ma(along x, y or z-direction, ) when applying this equation along say horizontal x direction, the direction of acceleration needs to be taken as it is a vector. i mean say 2 forces of 5 N and 3 N are applied on a 2 kg body that moves towards...

Thermal noise known as “Johnson noise” or “Nyquist noise” is well known and characterized. This noise is a result of thermal agitation of charge carriers inside a conductor. Its power spectral density is given by: v^2=4kTRwhere kB is Boltzmann's constant in joules per kelvin, T is the...

Can somebody please give me hints as to how to approach this problem? Three blocks are in contact with each other on a frictionless horizontal surface. [order: 2.8kg, 6kg, 7.7kg] A 667 N horizontal force is applied to the block with mass of 2.8kg. What is the net force on the block with mass...

Homework Statement The steel ball is suspended from the accelerating frame by the two cords A and B. The angles (they are on the inside) are both 60 degrees. Determine the acceleration of the frame which will cause the tension in A to be twice that in B. The acceleration is going to the...

I'm having a hard time understanding this. If a car that has a constant acceleration hits me let's say at 10km/h then at 100km/h will it exert the same amount of force on me? F= ma mass and acceleration are constant. But this doesn't seem right, does it? Do you guys know any good website or...

My textbook is Essential University Physics by Richard Wolfson. I'm attending Illinois Central College, and my course is Engineering Physics 1: Mechanics. It's calculus based. Homework Statement From the Text: "A florist asks you to make a window display with two hanging pots as shown in...

Hi guys! Can anyone please help me with these questions about the 1st and 2nd Law of Thermodynamics? First Law of Thermodynamics 1. An inventor has designed an electric car in the following manner. Batteries in the car power an electric motor that drives the vehicle. When the car coasts...

1. A 2.0 kg otter starts from rest at the top of a muddy incline 85 cm long and slides down to the bottom in 5.0 s. What net force acts on the otter along the incline. 2. Homework Equations - F=ma, maybe some more too. 3. The Attempt at a Solution I attempted this question for...

i need help with this problem please help (If you use a horizontal force of 30.0 N to slide a 12.0kg wooden crate across a floor at a constant velocity, what is the coefficient of kinetic friction between the crate and the floor?) PLZ HELP AHHHHH ITS DUE TMRW SO PLZ HELP

hmm...i was wondering is there any conditions for the use of Newton's second law?

Here is the problem I am working on: http://img45.imageshack.us/img45/5566/image0002bv6.jpg Here is my work: http://img177.imageshack.us/img177/7127/image0001zy6.jpg I cannot solve (2) for v since there are no real roots. When I set up the net forces in the x-direction in (1), should I...

only two forces act on an object (mass = 3.00 kg). 40.0N east and 60.0N north of east at 45 degrees. Find the magnitude and the direction (relative to the x axis) of the acceleration of the object. I don't really know where to begin.

A child slides down a slide with a 28 degrees incline and at the bottom her speed is preisely half what it would have been if the slide had been firctionless. Caluclate the coefficient of kinetic friction bewteen the slide and the child.

Hello to everyone! This is my first time that I use forums and I hope you will help me! Here is my question/problem: Is it possible using the second thermodynamic law to proove that: If the total work done by heat engine operated between two temperatures is zero, than it follows that...

hello:) i have a question: if i changed the mass of the ball on the pendulum, i assume that Changing the mass of the ball would not change the period of the pendulum because gravity pulls objects towards Earth at the same speed regardless of their mass. however Newton's second law says that...

can the second law of thermodynamics be defied? in other words, can mother nature be fooled somehow? have we (homo sapiens) accomplished such a thing with religion? for example, the seventh day of the week is nothing but a positive entropy change from sunset to sunset. can we somehow use that...

I have a couple homework problems that are causing me some trouble... 1. The weight of 600g of salami is: a) 0.061 N b) 5.9 N c) 61 N d) 5.9 kN I found the answer to be a) 0.061N because F=mg so m=F/g which is 0.6kg/9.8m/sec.squared. The answer is actually b) 5.9 N but I can not...

I hadn't seen this posted elsewhere already, and it certainly hits on a lot of topics which have been recently discussed: Irreversibility in Collapse-Free Quantum Dynamics and the Second Law of Thermodynamics by our esteemed member M. B. Weissman: Abstract: Proposals to solve the problems...

I know that violating physics laws is impossible; this is just a question, so just answer it and don't say that can't happen. Anyways, if there is a light object and a heavy object, and forces of the same magnitude are exerted on the the objects, and despite the heavier mass, the heavier object...