# What is Constant velocity: Definition and 200 Discussions

In optical storage, constant linear velocity (CLV) is a qualifier for the rated speed of an optical disc drive, and may also be applied to the writing speed of recordable discs. CLV implies that the angular velocity (i.e. rpm) varies during an operation, as contrasted with CAV modes. The concept of constant linear velocity was patented in 1886 by phonograph pioneers Chichester Bell and Charles Tainter.

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1. ### Finding shortest distance between an observer and a moving object

The rocket has constant velocity so we can write it's equation of motion as : $$\vec r = \vec r_0+t \vec v_0$$ We can write it for components along each axis : $$x = x_0 + v_{0,x}t$$$$y = y_0 + v_{0,y}t$$$$z = z_0 + v_{0,z}t$$We put known values in above equations...
2. ### Object A (in free fall) hits object B (ascending with constant velocity)

DofA = D0 + 1/2at^2 DofB = vt DofA = DofB, but how do I solve this and get the time when A and B hit?
3. ### I Cosmic Inflation Explained: Constant Velocity of Electromagnetic Radiation

C = sqrt(E/M)...this would suppose the ratio of the amount of energy vs. the amount of mass in the universe. If not, why not. If there is no mass, just energy, or much less mass at the moment of the hypothetical Big Bang, then, there C would be significantly higher, thus explaining cosmic...
4. ### I Comparing Clock Rates in Accelerated vs Constant Velocity Frames

@PeroK sent me here based on a discussion starting at https://www.physicsforums.com/threads/some-ideas-on-interstellar-space-travel.1006562/post-6550265. Summary: Someone claimed that an accelerated observer's clock (observer at 1g from Earth to halfway to Alpha Centauri, then -1g the rest of...
5. ### I Constant Velocity Motion in Relativity: Radiation Effects?

Does relativity imply that everything that goes at a constant velocity must not emit radiation of any kind?
6. ### B What experiments confirmed the constant velocity of light?

What other experiments, besides the M&M experiments confirmed the constant velocity of light? Thank you in advance for the response.
7. ### Constant velocity in a central force field

A body on a circular orbit in the field of a central force (satellites in gravity field of Earth; a charge in a magnetic field) is subjected to a force which is always perpendicular to its initial velocity v, hence in a time period dt it acquires an additional velocity dv, which is also...
8. ### Conservation of energy in a CM system moving at constant velocity

My book uses ##1/2m_1v_{1c}^2+1/2m_2v_{2c}^2=1/2m_1v_{1c}'^2+1/2m_2v_{2c}'^2## to show that the angles of deflection of the collision between two particles are the same in the centre of mass frame. However, I am doubtful that one can apply the conservation of energy to a "moving" system because...
9. ### On Bodies Moving with a Constant Velocity

Is the below Displacement time graph posible? if an object is in motion at a constant velocity, is it possible for it to stop instantaneously, or does there have to be a decelaration? According to Newton's first, an object will remain in its state of constant velocity unless acted upon by...
10. ### Zero Friction on the Moon: Driving at Constant Velocity Without Air Resistance

Suppose we are driving on moon (I mean there is not air resistance) at a constant velocity. Suddenly the car goes on an icy land (the friction is zero). What happens? In other words, if we drive at constant velocity and there isn't air resistance, Is there any friction force between tires and...
11. ### A The Higgs Field, constant velocity, and the acceleration of particles

I need some clarification on how the Higgs field work. The popular science explanation explains the effect on moving particles the way an object would be impacted by moving through a medium of maple syrup. I understand this is a very bad, inaccurate analogy. What I want to understand is does...
12. ### Maintain a constant velocity for a rotating wheel

I want to make a small mechanical calculator with no electric parts, nothing too advanced but a few binary gates capable of some basic functions. All the examples I were able to find were amazing but were still dependent on electricity to drive the mechanism. One possibility is a spring but I...

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14. ### Work done under constant velocity

Depending on the answer to this question, I may have others. Consider a one-dimensional ice rink. Rightwards is taken as the +x direction. A box of mass m slides leftward on the surface with a constant velocity v. Two people go to opposite ends of the box and apply equal and opposing forces...
15. ### A loaded railroad car is rolling at a constant velocity

Homework Statement A loaded railroad car is rolling at a constant velocity when it couples with a spring and dashpot bumber system. After the coupling, the motion of the car is defined by the relation ##x = 60e^{-4.8t} sin16t##, where x and t are expressed in millimeters and seconds...
16. ### Exploring the Relationship between Work and Constant Velocity

Hi! I've found some excercices and expanation of Work always consider a constant velocity, this is a net Force equal to cero. Like spring or gravity excercices related against a force applied. Does this relation with constant velocity has some usefull explanation why? Should I always assume...
17. J

### Applied force compared friction force at constant velocity

Homework Statement How does an applied force and a frictional force compare when moving at constant velocity? Homework EquationsThe Attempt at a Solution
18. J

### Constant velocity, constant acceleration?

Homework Statement Hi, I have a quick question about an experiment I am doing. I did an experiment where I rolled a ball over a flat surface and dropped a ball from a height, and I was asked if the ball rolling over the flat surface (1-d) motion is subject to constant velocity? I was also...
19. ### Faraday's law for constant velocity, area and B-field

Hi. If a planar wire loop is moved through a homogeneous magnetic field (field lines perpendicular to the loop plane) with constant velocity and no rotation, Lorentz force will move some electrons to one side of the loop, creating a potential difference. But how does this work with Faraday's...
20. ### Is Kinetic Energy Really Constant in Constant Velocity Motion?

I am really confused here. I have studied that if the kinetic energy of a moving body is not changing then the net work being done on the object is equal to zero. But when we are talking about a body moving upwards at constant velocity there is no change in its kinetic energy but there is still...
21. ### How does one find the normal force when not at constant velocity or at rest?

How does one find the normal force when the object is not at constant movement or at rest.
22. ### Uniform chain rising with constant velocity

Homework Statement A uniform chain lies in a heap on a table. If one end is raised vertically with uniform velocity v, show that the upward force that mus be exerted on the end of the chain is equal to the weight of a length z + (v^2/g) of the chain, where z is the length that has been uncoiled...
23. ### Charge at constant velocity emitting EM waves?

So far I have came to know that when a charge is accelerated the electric field magnitude around the charge changes and the effect is not felt instantaneously. The change in magnitudes of electric and magnetic field travels outwards at speed of light creating the so called EM wave. So the EM...
24. ### Constant velocity and work done

if a body is moving with constant velocity. Its work done will be? in my point of view Work done is change in energy. Constant velocity means no change in energy. So work done is zero am i right?
25. ### E-field of a moving charge at constant velocity

I came upon this page that provides the answer: http://farside.ph.utexas.edu/teaching/em/lectures/node125.html But I can't figure out what gamma(u) is. Could anyone help?
26. ### Angular momentum conservation and constant velocity as expla

I'm confused about situations involving rotating frames in which the angular momentum is conserved and the initial velocity does not change. I'll make an example. Take a rotating carousel (constant angular velocity) with no friction on it and a ball. At the initial time instant the ball has the...
27. ### Constant Acceleration Ratio to Constant Velocity

Homework Statement A car traveling at an unspecified constant speed passes a parked motorcycle cop. The motorcycle accelerated at an unspecified constant acceleration and reaches the car at unspecified distance d. At what point did the motorcycle's speed match that of the car, expressed as a...
28. ### Motion of mass connected to a spring at constant velocity

Homework Statement We have a mass m at x = 0 attached to a spring with spring constant k which is moving at constant velocity v such that the position of the spring is described by X = l + vt where l is the equilibrium length of the spring. Solve for the motion of the mass. Homework...
29. ### How can you ensure you pull a mass at a constant velocity

In an experiment I hope to carry out, one of my "constants" are velocity (constant velocity). I must say a way I will keep this value constant. For example I can not say "I will try my best to pull mass at a constant velocity" "I will take a video of the experiment. When I examine the video, I...
30. ### Value of friction with constant velocity

Homework Statement A block of mass "m" is pulled across a rough table by a string at an angle "θ" above the horizontal at a constant velocity. What is an equation for the magnitude of the kinetic friction force, fk? The answer that I was given was μk(mg-T*cos(θ)) Homework Equations Fk=Fn*uk...
31. ### Heavy chain moving upward at constant velocity

Homework Statement We have a heavy chain with length of L and weight of m placed on a table. we take an end of it and move it with constant velocity of v upwards. so each moment it gets heavier. If the force needed for this uniform speed is called F, and length of chain which is higher than the...
32. ### Zero Velocty is Constant Velocity?

Homework Statement In the Principles of Physics book chapter two in checkpoint 2 claims that If velocity of object is zero its a constant velocity.I am confused cause v=0 means there's no motion.Without motion we can't talk about constant velocity.I am confused.(The equation of object is...
33. ### Incline slope with friction

A tractor pulls a 5000kg asked up a hill at a constant velocity. If the hill had a constant grade of 30° with respect to the horizontal and there is a 10,000 N frictional force between the sled and the ground, what is the minimum force the tractor must exert on the sled? I think I'm supposed...
34. ### Tension between two objects moving at constant velocity

Homework Statement A railway engine of mass 100 tonnes is attached to a line of trucks of total mass 80 tonnes. Assuming there is no resistance to motion, find the tension in the coupling between the engine and the leading truck when the train: (a) has an acceleration of 0.020 ms-2, (b) is...
35. ### Constant Velocity : Does it means objects is at Rest

I have been studying that velocity = displacement / time. Now what if displacement / time always gives me same value - does it means that object is at rest as displacement is same then the body has not moved at all. So in above graph velocity is constant - ie displacement wrt to time is same...
36. ### Travelling to Mars at constant velocity? Weightless?

If I'm traveling on a spaceship at a constant velocity (say 10000 m/s) towards Mars will I feel weightless, or will I feel nearly weightless because I will still be slightly affected by gravity? I know that when astronauts are in the ISS they feel weightless because they are in a constant...
37. ### Calculating Distance and Time for Meeting at Constant Velocities

You and your friend are in building four equal-length blocks apart, and you meet for lunch. Friend is 1.2 m/s and you are 1.6 m/s. The restaurant is between the two building and you and your friend will arrive at the same instant if both of you leave the buildings at the same instant. In blocks...
38. ### Basic constant velocity graph question

Homework Statement A boat is sailing starting from x = 200m. When interpreting x(position) vs. t(time) graph for this boat with math models x = -20t + 200(t<=10), Is it right to say "The boat is approaching to the origin" ? (When t <= 10) Homework Equations x = -20t + 200(t<=10) The...
39. ### Mechanism to move a platform at a constant velocity

Hi all, I'm new here on Physics Forums and can't wait to delve into some juicy topics! I have a very practical problem that I need help with. I am doing a home project where I want to move a platform on wheels (loaded to a maximum of 70kg) in a 1.5m long straight line across the floor at a...
40. ### You are traveling on a straight road with constant velocity

Homework Statement At the beginning of a 10 sec. interval your position is measured to be 80 ft East with respect to a reference object. At the end of the 10 sec. interval your position is measured to be 965 ft East with respect to the same reference object. Determine your velocity at t = 3.45...
41. ### Acceleration of object at constant velocity in rotation?

I have some questions about acceleration that I'd like for someone to explain to me. As far as I know, acceleration depends on either change in velocity or change in direction (or both). So if I'm going 1m/s North constantly I'm not accelerating. However, what would be the acceleration if I walk...
42. ### Work, Force, Energy and power question about moving car.

Homework Statement A car has a power output of 45kW and travels at a constant speed of 30m/s. What force is the engine applying on the car? Homework Equations F=m*a W=ΔKE+ΔGPE KE=½mv^2 GPE=mgh W=F*d P=ΔE/ΔT gh_1+½v_1^2=gh_2+½v_2^2 The Attempt at a Solution I really have no clue. Since there...
43. ### Potential from a charge moving at constant velocity

Homework Statement Find the electric potential of a point charge with constant velocity ##v##. Homework Equations $$V(\mathbf{r}, t) = \frac{1}{4\pi\epsilon_0} \int \frac{\rho\left(\mathbf{r}', t - \frac{| \mathbf{r}- \mathbf{r}'| }{c}\right)}{| \mathbf{r}- \mathbf{r}'|}d^3r'$$ The Attempt...
44. ### Height and horizontal distance of a projectile

1. The problem: I need to find the height and horizontal distance reached by a projectile given only the vertical and horizontal velocities. Vv=120m/s Vh= 30m/s this is for an algebra based physics class, I'm very new to this stuff.Homework Equations : V=at+Vo X=1\2at^2 + Vo + Xo...
45. ### Why must a water skier at constant velocity lean back?

Homework Statement Why must a water skier moving with constant velocity lean backward? What determines how far back she must lean? Draw a free-body diagram for the water skier to justify your answers. Homework Equations Equilibrium: Fnet=0 and Torquenet=0 rcenter of...
46. ### Does Dumping Coal into a Moving Train Affect Its Velocity?

Ok so the question is a freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car? And I asked my teacher if the coal dumped in was stationary relative to...
47. ### Dashpot has constant velocity. Why?

I was watching this video for maxwell models help: The metal weight is being pulled down by force of gravity, which means there must be some net acceleration for it to be pulled down according to F = MA. My question is: if acceleration is a change in velocity, then how come the dashpot moves...
48. ### Finding distance given two different velocities and times?

Homework Statement On a straight track, a cart travels with a constant velocity of 2.5m/s for 9.0s. It then uniformly accelerates to a final velocity of 6.0m/s in 15s. Calculate the total distance traveled by the cart. Homework Equations Vavg = Vi+Vf/2 d=(Vf+Vi/2)x t d=Vi x t + 1/2at^2...
49. ### Force on charge particle with constant velocity

I have a problem. Anyone can help me? Two equal charges q move with equal velocity v. What is the force acting between two charges? The distance between charges is R and the angle between R and v is A.
50. ### Train with constant acceleration, catching it with constant velocity?

Homework Statement A train pulls away from a station with a constant acceleration of 0.4 m/s2. A passenger arrives at a point next to the track 6 s after the end of the train has passed the very same point. What is the slowest constant speed at which she can run and still catch the train...