What is Constant speed: Definition and 135 Discussions

In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel the knot is commonly used.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second (approximately 1079000000 km/h or 671000000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed.

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  1. N

    Understanding Light Speed: The Impact of an Observer Moving at 10% C

    An observer is moving at 10% the speed of light. A light ray whizzes past him. He measures its speed to be exactly 186000 miles/sec. What happens at the physical level that he does not measure the speed of light to be less? Has the time of the observer slowed down? Or what?
  2. A

    Dynamics - constant speed

    Homework Statement A motorcyclist travels around a curved path that has a radius of 450 ft. While traveling around the curved path, the motorcyclist increases speed by 1.10\frac{ft}{s}. Determine the maximum constant speed of the motorcyclist when the maximum acceleration is 7.00...
  3. B

    Vector Proof Of Constant Speed Means Perpendicular Acceleration.

    Homework Statement Prove that when speed is constant that V(T), and A(T) are perpendicular. Homework Equations I know this involves the dot product to show that the dot product of the vectors is zero. The Attempt at a Solution In my head I thought that since the speed is...
  4. S

    Discovering Constant Speed in Bosun's Chair Problem: Mechanics and Techniques

    Homework Statement In a typical bosun's chair problem (in which an individual is on a platform suspended in the air by a massless, frictionless rope- about a pulley- holding the opposite end of the rope) one asks what pulling force is required to set the bosun chair (and person) into movement at...
  5. W

    Finding Force of an Object on Incline w/ Constant Speed & Coefficient

    Homework Statement Hi guys and gals, Having an issue with this one and was hoping to get some help. I'm going to write out the equation and include an attachment with my free body diagram. Q: How long a force parallel to a 20° hill does it take to push a 100-lb box up the hill at a...
  6. S

    Plot motion of particle with constant speed and angular velocity

    Consider the problem of a particle sliding inwards with a constant speed c and starting at radius R=pc/Ω, on a platform rotating with a constant angular velocity Ω. Give a plot of the trajectory of the particle from r=R to r=0, for p=0.5, 1, 2, 6. I'm a little confused on how to do this...
  7. L

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  8. S

    DC motor turning at constant speed eventually

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  9. H

    Is Constant Speed Equal to Acceleration?

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  10. C

    Understanding Relativity: The Constant Speed of Light Phenomenon

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  11. B

    Work and Constant Speed: Exploring Kinetic Energy

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  12. N

    A person pushes a 10.0 kg lawn mower at constant speed with a force of

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  13. R

    Understanding Time Dilation: Explaining the Constant Speed of Light

    I've read that time and space dilate under acceleration to ensure the constant speed of light. I'm having trouble visualizing a scenario that illustrates this concept. Could someone please explain this to me? Thanks.
  14. E

    Wire moving at constant speed in a magnetic field

    So let's say I have a wire of length l moving in a uniform magnetic field of constant velocity. Now the induced EMF = Blv Constant velocity implies constant EMF generated per unit time. I even have a graph of EMF vs time in my textbook for such a situation showing a flat horizontal line...
  15. J

    Power concept related to gravity, constant speed, and air resistance

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  16. D

    HELP determine work needed to push a crate up a ramp at constant speed

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  17. A

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  18. K

    Magnitude of object with constant speed

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  19. K

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  20. D

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  21. rcgldr

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  22. A

    Pulleys moving down with constant speed

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  23. M

    Carousel physics. Calculating constant speed and distance.

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  24. V

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  25. J

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  26. F

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  27. E

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  28. A

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  29. T

    Constant speed vs. repeated acceleration

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  30. alyafey22

    Constant speed and acceleration.

    As we know that an object can move with constant speed and accelerate this can be expressed with an object moving along a curved path with constant speed ,hence it has an acceleration ... my question is how an object can have an acceleration and at the same time is moving with constant speed ...
  31. I

    The Constant Speed of Free Falling Objects

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  32. D

    Maximizing Distance for Clowns Shot from a Cannon

    In a circus act, clowns are shot from a cannon at a constant speed vo = 11.7 m/s. The angle of launch may be varied. a. What is the maximum distance D that a clown may travel, if the landing pad is at the same height as the mouth of the cannon? b. The circus master wants to shoot two...
  33. S

    How can something have both a constant speed and a precise location?

    How can something that moves at a constant speed for all reference frames have a specific location? Suppose two observers Alice and Bob are in motion with respect to each other so that they do not have a common inertial frame. But when both of them measure the speed of a photon, they find it...
  34. G

    Free Fall vs constant speed

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  35. J

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  36. F

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    hi ,this is my first post (and its not HW) i currently study dynamics of rigid bodies using (Hibbeler) and there's one thing about this type of motion (rolling) that just seems to elude me for any planar motion we have 3 equations \Sigma F_{{x}}={\it ma}_{{g_{{x}}}} \Sigma F_{{y}}={\it...
  37. M

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    Homework Statement The motor for an elevator can produce 14kW of power. The elevator has a mass of 1100 kg, including its contents. At what constant speed will the elevator rise? Homework Equations I'm not really sure. Probably Gravitational potential = mgh. Kinetic energy = 1/2mv^2...
  38. D

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  39. 1

    Light's constant speed and frames of reference

    Been reading up on physics out of pure interest, just learning really. Mainly started special relativity and learning about the inertial frames of reference. I think I understand that, but here's what I don't get. If from one inertial frame of reference moving at a constant 100 MPH, I toss...
  40. R

    Exploring the Universal Constant of Light Beyond Maxwell's Equation

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  41. D

    Astronaut traveling at constant speed, throws a wrench

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  42. P

    Force On Object With Constant Speed

    A sack of flour of mass 6.00 kg is lifted vertically at a constant speed of 4.00 m/s through a height of 18.0 m How great a force is required? F=ma I found the force that the sack has on the Earth (58.8N), but don't understand how I am suppose to find what force is being applied to...
  43. O

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    Homework Statement A car travels along a straight line at a constant speed of 48.5 mi/h for distance d and then another distance d in the same direction at another constant speed. The average velocity for the entire trip is 30.5mi/h. a) What is the constant speed with which the car moved...
  44. L

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  45. I

    Need Help with problems involving constant acceleration and constant speed. :/

    Homework Statement At the instant the traffic light turns green, a car that has been waiting at an intersection starts ahead with a constant acceleration of 3.60 m/s^2. At the same instant a truck, traveling with a constant speed of 20.5 m/s, overtakes and passes the car. How far beyond its...
  46. M

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  47. O

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  48. S

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  49. O

    Move a Part at Constant Speed Under its Own Weight

    How can I make a hanging weight attached to a wire move at a constant speed under its own weight? The mass of the weight may vary and is not known beforehand.
  50. J

    Blocks moving on frictionless incline at constant speed, accleration

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