Rest Definition and 549 Threads

Homework Statement A proton has an initial speed of 4.9 105 m/s. (a) What potential difference is required to bring the proton to rest? (b) What potential difference is required to reduce the initial speed of the proton by a factor of 4? (c) What potential difference is required to...

Homework Statement A particle's position is r =(ct^2−2dt^3) i hat+(2ct^2−dt^3)j hat. where c and d are positive constants. part a) Find expressions for times t > 0 when the particle is moving in the x-direction. part b) Find expressions for times t > 0 when the particle is moving in the...

Homework Statement "(a) Draw a quark-flow diagram for the weak decay \pi^{-}\rightarrow\mu^{-}+\overline{\nu_{\mu}} . Explicitly include the appropriate intermediate vector boson. (b) By considering the production of \mu^{-} and \overline{\nu_{\mu}} in the rest frame of the vector boson...

If we use only rest mass as the source of gravity, but use the rest of general relativity. What are the differences with observations. Excluding cosmology and dark energy. I mean real observations, not just theory. I exclude from the question, cosmology, dark matter and dark energy. In my...

Hi all, I think this is a self help question, but I still need some advice. I am a Post Graduate Mechanical Engineer and started a job from past 6 months. Initially I enjoyed Engineering because I liked to be with passionate people and building some things. In addition I enjoyed learning...

Science wants to be correct, Every observable object on the planet is not at rest, we are all moving in space. Have any calculations been attempted to add a constant or variable to make calculations not start at rest, but at a certain motion? How can scientists reasonable say a statement...

I am confused on an issue relating to gluons and mass. As I understand it, quarks don't actually have a lot of rest mass. In fact, most of the rest mass found in Hadrons arises from the interactions and energy of the Gluon field between quarks(??). This sounds like GR to me, meaning that the...

(1.) I have a "particle in motion" problem that is asking me when a particle is at rest, which I understand to be when velocity = v(t) = 0, so v(t) = - (π/4) sin (πt/4) = 0. The given answer is as follows: - (π/4) sin (πt/4) = 0 sin (πt/4) = 0...

I've come to the conclusion that i don't understand at all the concept behind inertia. How can we know when an object stays at rest or at constant velocity? (take for example a girl in a rope. She would tighten her grip on the rope until the tension balances the force of gravity (assume rope is...

My question concerns the delta++ baryon. I understand that the rest mass of quarks makes up a very small percentage of the total mass of a baryon, but I don't understand exactly what it is about delta ++ (uuu) which makes it have greater rest mass than a proton (uud). If anyone can explain...

Homework Statement A powerboat, starting from rest, maintains a constant acceleration. After a certain time t, its displacement and velocity are r and v. At time 2t, what would be its displacement and velocity, assuming the acceleration remains the same? a) 2r and 2v b) 2r and 4v c) 4r and...

If neutrinos were massless, they would have to travel at c. But now we know they have mass, so they must travel at speeds less than c. But (all?) other massive particles can be brought to rest. Why not neutrinos? Is there a theoretical reason that forbids it?

Basic question I'm sure, but here goes; If the following is correct; An object may be considered to be 'at rest' when there are no inertial forces acting upon it (ie; it is not accelerating). A satellite is at rest because it is in freefall. A person standing still on the Earth's...

Homework Statement An electron is traveling through a magnetic field B=(Bx, By, Bz). Find an expressions for the electric field E required to keep the electron's velocity constant at v=(0,vy,0). Hence, show that E and B are perpendicular.Homework Equations F=q(v cross B) F=qEThe Attempt at a...

Here's the Cassini image from Saturn. Suppose I map an x-y coordinate system on that picture with the Earth (that pale blue dot down there) at the origin. Without looking at anything else, can you place points at the perimeter of the square picture, giving the angle pointing to where the sun...

Homework Statement A smooth sphere of mass m collides obliquely with a smooth sphere of mass 2m which is at rest.The velocity of the mass m was 8i + 4j before impact, where i is along the lines of centres at impact.the m mass is then deflected through 90 degreese by the impact. find (i) its...

Homework Statement A car of mass m takes off from rest around a circular track of radius r . Speeding up at a constant rate, the car takes t seconds to go around the track once. What is the magnitude of the net force acting on the car at the end of the trip? Homework Equations a_rad...

I need to find the value of the first term for this geometric series. Sn = 33 tn = 48 r = -2 I know that I have to take the formulas tn = t1 x r^(n-1), and Sn = [t1 x (r^n) - 1] / (r - 1), and isolate t1 for the first formula and then input that into the second, but I don't know the actual...

I push a ball on the ground and it comes to rest after some time. It is a case of motion turning into rest. I think every person, whether he be on Earth, Moon, or in any other part of the universe will see the ball coming to rest. If you attach a reference frame to the ball itself, the...

I had posted this question here : http://physics.stackexchange.com/q/69003/540 I guess its appropriate to post links in here as question. This question is really puzzling me and any suugestion/comments are much appreciated and welcome.

What happened to the rest? ## x_1=2u-v \\x_2= u+v \\ x_3=v-u\\## So the book has this arranged in a 2-by-3 matrix below ## \left[ \begin{array} { c c } 2 & -1 \\ 1 & 1 \\ -1 & 1\\ \end{array} \right] ## Then end up taking the determinant of this matrix, but the two by two part at the...

My understanding is that the presence of energy and matter curve spacetime. Is a photon considered energy? If so, how can it curve spacetime while having zero rest mass?

I have two examples.Terminal velocity-When the forces are balanced,the person continues to fall down at a constant velocity. Holding a Box-When the forces are balanced,the box stays at rest. A question about power in my textbook is:A crane lifts a box of weight 100N up at a constant velocity.The...

Homework Statement An object is at rest and stays at rest, but a rope attached to it is pulling with increasing force. What is the acceleration? Homework Equations F=ma The Attempt at a Solution The solution is that acceleration is constant and 0. Obviously a= dv/dt =0, since...

Homework Statement Two objects accelerate from rest with the acceleration of Object A twice that of Object B. After accelerating for a given time, Object A will have traveled how many times the distance of Object B? The Attempt at a Solution How can I find out mathematically? I know that...

This isn't a homework question, though it kind of relates to a practical I did recently. Sorry if it's posted in the wrong section! So, why are only 2 photons formed from positron-electron annihilation at rest? I understand why you can't have just one, as then you won't get conservation of...

1. a) A relativistic proton has a momentum of 10x10^-18 kg*m/s. The rest energy of a proton is 0.150nJ. The kinetic energy of the protoon b) In this situation the speed of the proton is? 2. E=MC^2 P= MV/sqroot(1-(v^2/c^2) K=[MC^2/ sqroot(1-v^2/c^2)]-[mc^2] 3. The algebra in this problem...

Sorry if this looks a bit premature for evolution; just can’t stop asking! Dolphins, human and Crovidaes are living in three different environments, within these three human (land inhabitant) reached the most advance brain function, although our brain could not use many of its ability based...

Homework Statement "In a drag race a car starts at rest and attempts to cover 440 yd in the shortest possible time. The world record is 5.637s; the final speed was 250.69 mi/h at the 440 yd mark" a)What was the average acceleration? b)Prove that the car did not move with constant...

Homework Statement A 5.0kg mass is accelerated from rest at the bottom of the 4.0 m long ramp by a falling 20.0kg mass suspended over a fictionless pulley. The ramp is inclined 30º ramp from the horizontal, and the coefficient of kinetic friction = .26. a. Determine the acceleration of the...

16. A 1-kg mass of iron is heated through 1000 0C. Find the increase in its rest mass. Specific heat of iron is 500 Joule per kg per 0C

Homework Statement . Suppose you are pushing a 60 N uniform crate at rest with a horizontal force of 40 N exerted at the top as shown. The crate is a cube with length of L. If the coefficient of static friction between the crate and floor is 0.75, which statement below is correct? (Hint...

Homework Statement A particle of mass m kg is traveling in a horizontal straight line with a velocity u m/s. It is brought to rest by means of a resisting force of magnitude km(2u - v), where v is the velocity of the particle at any instant and k is a positive constant. Find the distance...

Homework Statement Three printers [X, Y, Z] are placed on top of each other on a table. What force does the middle printer exert on each of the other two printers. x is on top, y in middle, and z on bottom. x = 4 kg, y = 3 kg , and z = 2 kg 2. F = ma The Attempt at a Solution...

Homework Statement A charged particle is moving in a magnetic field. what is the electric field E needed to bring the particle to a rest at 100 us, and v is 1 km/s Homework Equations I know the magnetic force is q*vxB and Fc=(mv^2)/r I have all the parts I think to solve this, I'm...

Let me phrase the entire question: How is acceleration equivalent to rest in a gravitational field (without tidal effects)? It's not that I am incapable understand the implications of this--it comes from a quote by DaleSpam and it seems to be rich--I just cannot break down the language he is...

Homework Statement http://postimage.org/image/sezpli4pv/ Having some difficulty understanding some concepts of Work and Energy. Homework Equations W = F * D KE = 1/2 mv^2 PE = mghThe Attempt at a Solution A) Speed is at B is less than the speed at D, because B has more PE than D B) False...

Hello, Homework Statement A gearbox and flywheel are as shown in FIGURE 4. The output shaft rotates in the opposite direction to the input shaft at 5 times its speed. The gearbox has an efficiency of 92%. If the flywheel is solid, has a mass of 50 kg, a diameter of 1.5 m and is to...

Hello all . Rest mass of Hydrogen is more than rest mass of one proton and one electron ? I mean virtual photon between electron and proton give extra mass to Hydrogen ? Like gluon between quarks ? and another example : mass of solar system is more than mass of One to One planets and sun...

Homework Statement A plank with length L is held in a place by two supports, one plank at one end A and the other a distance 5L/12 from the same end B, and is otherwise only affected by gravity. The plank has mass m. How can the vertical force on the plank be determined? Homework...

Homework Statement Imagine a rubber beam. One en is fixed and the other is pulled down 5cm and released. The beam wobbles until it comes to rest. Independent (what I change): length of rubber beam Dependent (what I measure): time to come to rest Controlled (what stays the same)...

An ice sled powered by a rocket engine starts from rest on a large frozen lake and accelerates at +38 ft/s2. After some time t1, the rocket engine is shut down and the sled moves with constant velocity v for a time t2. Assume the total distance traveled by the sled is 15750 ft and the total time...

Homework Statement A pion in its rest frame decays into a muon and a neutrino. Find the velocity of the muon and its mean-lifetime in the pion rest frame. (I've done this part). The muon decays into an electron and two neutrinos. If the two neutrinos happen to travel in the same direction...

I know that the rest frame of the photon is a non inertial reference frame. In that sense obviously the physics will not be Lorentz co-variant and so on. I have the following question Is possible to define a coordinate transformation from an inertial reference frame to the rest frame of a...

Homework Statement consider a pion decaying into 2 photons. In the rest frame of the pion, the two photons must emerge back-to-back photons are equally likely to emerge in any direction. determine the rest frame angular distribution of the emerging photons. Homework Equations ΔP=f(θ)Δθ is...

Hi, There have been very few discussions on this topic in the internet. Is it better to get a PhD degree from the UK or from other European countries such as Belgium , Spain ,Germany, Netherlands,Sweden etc ? I have shortlisted for my PhD, University of Strathclyde and Heriot Watt in UK...

Homework Statement An unstable particle, initially at rest, decays into a pro- ton (rest energy 938.3 MeV) and a negative pion (rest energy 139.5 MeV). A uniform magnetic field of 0.250 T exists perpendicular to the velocities of the cre- ated particles. The radius of curvature of each...

Outrageous way to be put to rest :D I was thinking the other day about when I die, I have come to the conclusion of what I want but how feasible is it right know I have no idea but here goes. I want to be put inside a completely air tight, radiation proof, heat proof containing, shot up into...

A uniform thin rod of length 0.500 m and mass 4.0 kg can rotate in a horizontal plane about a vertical axis through its center. The rod is at rest when a 3.0 g bullet traveling in the rotation plane is fired into one end of the rod. As viewed from above, the bullet's path makes angle θ = 60°...

I was reading the Wikipedia page on "Mass in Special Relativity" (http://en.wikipedia.org/wiki/Mass_in_special_relativity) and I came across two equations: M = m/sqrt(1-v2/c2) and p = mv/sqrt(1-v2/c2) along with the following quote: Einstein's comment seems to suggest that the...