Laws Definition and 1000 Threads

Personally I'm on the border-line between atheist and agnostic however the following statement gets me thinking. It is a statement that every physicist can resite without having to think; "Every object remains in a state of rest or in uniform motion until acted on by an external force"...

I need to show that P<->Q is logically equivalent to ( P ^ Q ) v ( ~P ^ ~Q) So far I have P <-> Q is equivalent to ( ~P v Q ) ^ ( ~Q v P ) by a example I have no idea where to go from here

14. According to Newton’s _____ law, an object with no net force acting on it remains at rest or in motion with a constant velocity. A. Third B. Fourth C. Second D. First (for this question I related it to the concept of Newtons first law) Is this correct

http://i49.tinypic.com/1yu634.jpg this is a part of the solution " the is a voltage drop on capacitor C1 which makes current shock on C1 and a current shock on R2 and R3 and it makes a KVL contradiction on the right branch and the outer branch. and that's why the continuety laws...

How does inverse square law of gravity relate to the inverse square law of electromagnetic radiation (e.g. illumination)? How come gravity and EMR propagate identically even though they are different forces?

Newton's laws cannot be proven! As far as i know, Newtons laws are... 1st Law-- A body at remains at rest and a body at uniform motion remains at uniform motion unless an external for acts on it. 2nd Law-- F=ma 3rd Law-- Every action has an equal and opposite reaction. No method has...

In this text is explained why our universe exists and why there are nature’s laws. The explanation is given in two parts: Part 1: Why does our universe exist? Part 2: Why does nature’s laws exist? The explanation uses concrete examples, to make the text as comprehensible as possible. At the...

Homework Statement Hi there, I just want to see if I am doing these questions correctly. Any help with this would be great. The question and circuit diagram are in the attachment. CheersHomework Equations Kirchoff's Laws for voltage and current. I'm not too sure if there is an equation, you...

Not a homework question, but I am trying to understand some stuff in Leibniz's 17th century "natural philosophy" which got me realizing that I don't have a clear grasp of my high school physics from 40 years ago. Imagine a closed system consisting of 2 objects, and imagine a perfect elastic...

Homework Statement A person pushes a 14.0-kg lawn mower at constant speed with a force of F= 88.0N directed along the handle, which is set at an angle of 45 degrees to the horizontal. (a) Draw the free-body diagram showing all forces acting on the mower. Calculate (b) the horizontal friction...

Homework Statement A person stands on a scale on an elevator. If the mass of the person is 96.34 kg and the elevator travels upward at a constant speed of 4.42 m/s, what is the reading on the scale? Homework Equations m = 96.34 kg V avg = 4.42 m/s The Attempt at a Solution I...

Homework Statement Say I have a circuit that splits into three parallel wires. They each have a resistors on them of 2, 3, and 4 ohms respectively. They reconnect and their final current is 10 Amps. Is there a more intuitive way to find the current on each wire based on the ratios of ohms...

Hi all, I've been recently digging into SR in my attempts to better understand electromagnetics. One thing that has been giving me trouble is the force transformation laws, which seem to give rise to some pretty gnarly paradoxes, one of which I've listed here: Consider two objects, where...

Homework Statement 8. (II) A car can decelrate at -4.80 m/s^2 without skidding when coming to rest on a level road. What would its decelration be if the road were inclined at 13 degrees uphill? Assume the same static friction force. Homework Equations Ffr = MuFn F = ma The...

I'm new to studying physics. Are the laws of nature and the laws of physics synonymous with each other? Thanks!

I've argued in other threads in this and other forums against strict determinism (non probabilistic) on philosophical grounds. The probabilistic formulation of quantum mechanics is still the standard view, but it seems to irritate some who post in PF. They would seek a fully deterministic theory...

Homework Statement A baseball player hits the ball straight up in the air with a velocity of 18.0m/s. As soon as the ball is hit, the runner on third base dashes toward the home plate. The distance between third base and home plate is 27.4m. Where will the runner be with reference to home...

Homework Statement A 65kg swimmer jumps of a 10m tower. a) Find the swimmer's velocity when hitting the water b) The swimmer comes to a stop 2.0m below the surface. Find the net force exerted by the water. Homework Equations F=ma? I don't know the rest, which is part of the problem...

A 6.0L flask contains a mixture of methane, argon, and helium at 45C and 1.75atm. If the mole fractions of helium and Argon are 0.25 and 0.35, respectively, how many molecules of methane are present? V = 6.0L T=318.15K Ptotal=1.75atm mole fraction: XHe=0.25 XAr=0.35 XCH4=0.40...

Homework Statement Calculate limit Using Limit Laws Homework Equations Lim x+2/X^3+8 as X-->(-2) The Attempt at a Solution Ok so, I'm a little stumped as to what trick I need to pull out of the bag for this one. Obviously the function goes to 0/0, but I can't seem to factor...

Homework Statement A box is given a push so that it slides across the floor. How far will it go, given that the coefficient of kinetic friction is 0.18 and the push imparts an initial speed of 4.1 m/s? Homework Equations MG of the object = mass * 9.8 Friction = mg * 0.18 The...

Homework Statement A block of mass m lies on a wedge of mass M as shown in figure. Answer the following parts separately. (a) - With what minimum acceleration must the wedge be moved towards right horizontally so that the block m falls freely? (b) - Find the minimum friction co-efficient...

¿what is the domain of validity of inverse square laws of Newton and coulomb? I think (correct me if this is false) that at the small scale these laws have been verified accurately , but ¿what happens with large distances? :rolleyes: . ¿Have been done an experiment which measured the...

The particle of mass 'm' is moving with the laws ... Homework Statement The particle of mass 'm' is moving with the laws ... Homework Equations a. x=3t2+4 b. x=106t-t2 c.x=1000t-5t2 d.x=t2-20t e.x=50t-2t2 in what case the value of the force acting on the particle is the...

How does (ln(x))^(1/x)=ln(x^(1/x))? A friend told me this was a true statement but could'nt prove it. If that isn't true, then how would you find the lim x->0 of (ln(x))^(1/x) using L'Hospital's Rule?

Homework Statement Three crates are arranged. Their masses are m1=29.8, m2= 15.3, m3= 27.3. The applied force of 910 N is directed horizontally and the coefficient of friction is u= .277 WHAT IS THE MAGNITUDE OF THE CONTACT FORCE BETWEEN M1 and M2? WHAT IS THE MAGNITUDE OF THE CONTACT...

We keep searching for the Physical Laws but is anyone looking for the Laws that brought them about? Is it not inconsistent to expect Physical Laws to have no cause? Foundations of The Quantum Logic

Homework Statement Three crates are arranged. The masses of the crates are m1= 29.8kg, m2= 15.3kg, and m3=27.3kg. The applied force of 910 N is directed horizontally, and the coefficient of friction is u= .277. what is the acceleration of the three masses and the magnitude of the...

Homework Statement How much tension must a rope withstand if it is used to accelerate a 1000 kg car vertically upward at 0.80 m/s2? Ignore Friction. Homework Equations fay= ma ? mg-fn=0 The Attempt at a Solution F=MA F=1000kg * .8 F= 800 WRONG!

Homework Statement A 1380kg car is moving due east with an initial speed of 27 m/s . after 8.00s the car has slowed down to 17.0 m/s . Find the magnitude and direction of the net force that produces the deceleration Homework Equations Net force of x= MAx Net force of y= MAy The...

Homework Statement A orbiting satellite stays over a certain spot on the equator of (rotating) Mercury. What is the altitude of the orbit (called a "synchronous orbit")? Mercury mass = 3.3022 e23 kg Mercury Radius = 2439.7 km Homework Equations T^2 = (4\Pi^2/GM) * r^3 and that's...

I'm having a lot of trouble trying to figure out some of these problems. If people could help me, it'd be greatly appreciated! 1. A 50.0-kg person takes a nap in a backyard hammock. Both ropes supporting the hammock are at an angle of 15.0° above the horizontal. Find the tension of the ropes...

Homework Statement Some people believe that the Moon controls their activities. The Moon moves from being directly on the opposite side of Earth from you to be being directly overhead. Assume that the Earth-Moon (center-to-center) distance is 3.82 multiplied by 108 m and Earth's radius is 6.37...

Ok, firstly I just want to say I have a layman's interest in physics. But from my limited understanding physicists use the theory of general relativity to understand big things like stars and galaxies and use quantum mechanics to understand the very small things like atoms and sub-atomic...

Consider the following cyclic process: Each cycle 800J of Energy is transferred from a reservoir at 800K and 600J of energy from a reservoir at 600K. 400J of heat is rejected to a reservoir at 400K and 1000J of work is done. I think that the process doesn't violate the first or second laws...

A 500N force acts in a northwesterly direction . A second 500N force must be exerted in what direction so that the resultant of the two vectors points westward? i think the answer is southwesterly direction but I am not sure. :confused:please help.

Homework Statement A 0.54kg ball falls from rest at a height of 26m and rebounds up 16m. If the contact between the ball and ground lasted 1.8ms, what average force was exerted on the ball? Homework Equations F=ma v²=v0²+2a(x-x0) v=v0+at 1000ms=1s (1.8ms is 0.0018s) The Attempt at...

The pine tree air freshener hanging from the rear view mirror makes an angle of 27.9 degrees with the vertical while a car is acceleration a)What is the car's acceleration ax=gsin(theta)=9.80*sin(27.9)=4.59 b)What is the tension in the string of the 100g air freshener? ax=T/m=4.59(100)=T...

Homework Statement A train is traveling up a 3.73 degrees incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction. a) How long does it take for the last car to come to rest momentarily? b) How far did the last car travel before momentarily coming to...

Some laws of nature are not fundamental. These laws are explained why more fundamental laws. These more fundamental laws would be explained by more fundamental, deeper laws. Assumpting that this process do not continue indefinitly. We will eventually arrived at a set of fundamental laws, S. Why...

Homework Statement "Blocks A, B, and C are placed as in the figure and connected by ropes of neligible mass. Both A and B weigh 25.0 N each, and the coefficient of kinetic friction between each block and the surface is 0.35. Block C descends with constant velocity. a) Draw separate free body...

Homework Statement What is the acceleration of a 35 kg block of cement when pulled sideways with a net force of 150 N? Homework Equations what i did was f=ma a=m/f and just plugged the numbers in The Attempt at a Solution i got 4.2 but when i entered it into the assignment it...

Homework Statement To model a spacecraft , a toy rocket engine is securely fastened to a 2.00-kg large puck, which can glide with negligible friction over a horizontal surface, taken as the xy plane. The engine exerts a time-dependent force, F = (8.00 î – 4.00t ĵ) N, where t is in seconds...

Projected Up an Incline A block is projected up a frictionless inclined plane with initial speed v1 = 3.43 m/s. The angle of incline is θ = 32.5°. (a) How far up the plane does it go? (b) How long does it take to get there? (c) What is its speed when it gets back to the bottom...

Homework Statement There is a table with two masses hanging from the sides, each weighing 100N, on the table there is a scale, what would this scale read? A) 100N B) 200N C) 0N Homework Equations Fnet = Mass1 -Mass2 The Attempt at a Solution Since one tension in one string...

1) If air contains 1% AR by volume, what is the mass of Argon in a 2L balloon of air at 25 degress celsius? 2) If for a real gas, P = RT(V - b) - a/V^2 where a and b and R are constants, P = pressure, T = temperature and V = volume. What does a large a value represent in a real gas? 3)A...

Homework Statement Two astronauts are unloading scientific equipment from the spaceship that has just landed on the Moon surface. To prevent a box from sliding down an inclined ramp, astronaut A pushes on the box in the direction parallel to the incline, just hard enough to hold the box...

Homework Statement An 81 kg man lowers himself to the ground from a height of 10.6 m by holding onto a rope that runs over a frictionless pulley to a 60 kg sandbag. (a) With what speed does the man hit the ground if he started from rest? (b) What can he do to make him hit the ground slower...

First post =] Requesting guidance with this particular problem: Homework Statement A 1.20 kg object is moving in the x direction at 14.4 m/s. Just 3.31 s later, it is moving at 28.8 m/s at 34.0 degrees to the x axis. a.) What is the magnitude of the force applied during this time...

Homework Statement A worker pulls horizontally on a rope that is attached to a 10 kg crate that is resting on a rough floor. The coefficients of static and kinetic friction are 0.5 and 0.3 respectively. The worker pulls with a force of 45N. What is the frictional force exerted by the...