Velocity Definition and 1000 Threads

The velocity of an object is the rate of change of its position with respect to a frame of reference, and is a function of time. Velocity is equivalent to a specification of an object's speed and direction of motion (e.g. 60 km/h to the north). Velocity is a fundamental concept in kinematics, the branch of classical mechanics that describes the motion of bodies.
Velocity is a physical vector quantity; both magnitude and direction are needed to define it. The scalar absolute value (magnitude) of velocity is called speed, being a coherent derived unit whose quantity is measured in the SI (metric system) as metres per second (m/s or m⋅s−1). For example, "5 metres per second" is a scalar, whereas "5 metres per second east" is a vector. If there is a change in speed, direction or both, then the object has a changing velocity and is said to be undergoing an acceleration.

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  1. G

    Acceleration and Displacement from a Velocity vs. Time Graph

    Please could I ask for help with the following question: Part (a) is no problem. Acceleration is the gradient of the graph in regions OA and AB which gives 3 and 0.5 Part (b), I believe, requires me to calculate the greatest and least value of the gradient of the curve in region BC Part...
  2. B

    Distance Velocity Graph: What Does the Area Represent?

    Summary: Gradient = Acceleration(?) Area = Time (?) Good evening, I have a problem that presents itself in a distance (y) velocity (x) graph. I've never come across this, and in my Physics textbook, the section dedicated to graphs does not have it. My question is, what does the area of the...
  3. L

    Average velocity and instantaneous velocity

  4. Like Tony Stark

    Calculating the radius of curvature given acceleration and velocity

    Well, what I've done so far is calculating the magnitude of velocity and acceleration replacing ##t=2## in ##\theta (t)## and ##r(t)## so I could get the expressions for ##\dot r##, ##\dot \theta##, ##\ddot r## and ##\ddot \theta##. But that's not my problem... my problem is related to the...
  5. Like Tony Stark

    Decomposing velocity vectors into polar axis

    Well, I drew the polar and standard axis centered in the particle and wrote which angles were equal to 60° so I could decompose the velocity. The problem says "moves towards it (the radar) with velocity v=5 m/s, so that's one of the components. But I realized that the velocity "cuts" the angle...
  6. PainterGuy

    Boltzmann distribution and the number of molecules with a certain velocity

    Hi, You could skip these details and find the main question at the bottom. I added the details for the sake completeness and context. Thanks. Boltzmann distribution of molecular speeds provides an insight into the different speeds the molecules of a gas are moving around with. It provides you...
  7. K

    Velocity Map Imaging: Understanding 3D Reconstruction

    Hello! I am a bit confused about the image reconstruction for velocity map imaging. As far as I understand, at the interaction point, ions are produced in a Newton sphere which gets projected on a 2D screen (such that all the particles with the save velocity get mapped on the same point). What...
  8. Abhimessi10

    Engineering Houston's piezoelectric method for finding the velocity of light

    Crystal acts as a diffraction grating.Although I don't know what that means.
  9. karush

    MHB 4.1.26 graph of velocity over acceleration graph

    ok not finding this easy but the red is mine drawn over the given book graph also want to convert the whole thing to tikx graph
  10. M

    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. jisbon

    Relative velocity of a ball thrown inside a moving truck

    Hi all, Not sure on how to start this question in the first place, but from what I gathered from the data given I managed to derive this from the question: ##\theta = 53.13\deg## Let inside truck be t, final position be f, and ground be g ##D_{ft} = L## ##D_{fg} = xL## Also, for velocity...
  12. E

    Relative velocity of two gravitationally attracting spheres

    There have been some other threads on similar problems but none address one specific point I'm confused about. The change in GPE of a body is the negative of the work done on that body by a gravitational field between two points; by this logic, since the same (but opposite) gravitational forces...
  13. Seth Greenberg

    What is the angular velocity in the center of a rotating disc?

    I have a disc. The center of the disc is its center of mass and the motion of the disc is purely rotational (no translation). What is the angular velocity in the center of the rotating disc?
  14. Prabs3257

    Velocity of the center of mass in constrained motion

    I tried getting the velocity of a which by using constraint came out to be 3 and by using the eqn for vcom i got the ans as 3.5 i just want to confirm is this the correct answer
  15. jisbon

    Circular motion -- Find the angular velocity at t=3

    Hi everyone. Do correct me if I am thinking wrongly. So to find angular velocity, won't I just have to integrate angular acc = 2t, which means angular velocity = t^2? Hence, won't the answer be 3^2=9? The answer seems to be 5.43 :/ Thanks
  16. D

    Instantaneous versus average velocity?

    I have a hard time understanding what this problem even means. So I can't even begin with it.
  17. karush

    MHB Cp2.63 find the initial velocity

    cp2.63. The acceleration of a particle is given by $$a(t)=-2.00 \, m/s^2 +3.00 \, m/s^3.$$ a. find the initial velocity $v_0$ such that the particle will have the same x-coordinate at $t=4.00\, s$ as it had at $t=0$. b. What will be the velocity at $t=4.00 s$ ok sorry but I don't even know...
  18. karush

    MHB What Is the Total Distance Traveled by the Particle from t = 0 to t = 3?

    $\tiny{207 \quad DOY}$ A particle moves along the x-axis. The velocity of the particle at time t is $6t - t^2$. What is the total distance traveled by the particle from time $t = 0$ to $t = 3$ ? $(A)\,3 \quad (B)\,6 \quad (C)\,9 \quad (D)\,18\quad (E) \, 27$ ok think this is correct...
  19. Shivam

    Calculating Safe Velocity: Why Is 4th Option Incorrect?

    1). I calculated maximum safe velocity using the equation - V(max)=√200x10x0.2 =20m/s So the speed at which car is traveling is greater than the safe speed.. So the car should skid. So why 4th option is not correct ?
  20. S

    Relation between mass distribution and angular velocity

    Is E the correct answer because I think angular velocity is independent of mass distribution of the object? Thanks
  21. G

    Determination of the velocity of a particle in a hollow cone

    Hi, please could I ask for help with the following question: A smooth hollow circular cone of semi-angle α, is fixed with its axis vertical and its vertex A downwards. A particle P, of mass m, moving with constant speed V, decribes a horizontal circle on the inner surface of the cone in a plane...
  22. Adesh

    A question of kinematics involving a changing velocity vector

    The statement "at the initial moment of time v ⊥ u and the points are separated by a distance l " gives us a picture like the one which I have added in attachment. As the time passes velocity vector v would gradually change from fully vertical to fully horizontal in order to meet point B. Now...
  23. PainterGuy

    Equalization of velocity components and momentum conservation

    Hi, I understand and I'm sorry that there are going to be many loopholes in what I'm trying to put together and that too without any mathematical formulation but I don't even know where and what to start with. Suppose we have a finite length insulated hollow cylinder filled with with air at 1...
  24. P

    Why is the Lorentz force linear with velocity?

    I am working on derivation of Lorentz force. (I know that Lorentz force is in some sense definition of fields, but still there is nontrivial dependence on velocity). I want to derive that the force is linear in components of velocity, so for example $$F_x=q(E+Av_x + Bv_y + Cv_z ),$$where ##A...
  25. A

    Velocity Question for a Car Accelerating Down a Road

    240/8=30.
  26. karush

    MHB 4-39 magnitude of its velocity after falling 10.0m

    a) what is its speed after falling to 2.00s motion formula $v=u+at$ so $v = 6.00 \dfrac{m}{s} + 9.81 \dfrac{m}{s^{\cancel{2}}}{2.00 \cancel{s}} = 27.6 \dfrac{m}{s}$ b) How far does it fall in 2.00s distance formula $d= ut + \dfrac{1}{2}at^2$ so...
  27. karush

    MHB 2.6 Calculate the average velocity of the car in different time interval

    OK I just had time to post and hopefully ok but still typos maybe the graph was done in Deimos wanted to try tikx but not sure about the polynomial trying to as many physics homework before classes start on Aug 26 Mahalo
  28. G

    Calculation of minimum angular velocity of a mass on a spinning plate

    Problem Statement: How to calculate minumum angular velocity of a mass on a spinning plate Relevant Equations: f=mrw^2 Hi, here's the question: a) A rough horizontal plate rotates with a constant angular velocity of w about a fixed vertical axis. A particle of mass m lies on the plate at a...
  29. samm12345

    What is the final angular velocity of each cylinder

    Problem Statement: The uniform 4-kg cylinder A, of radius r = 150 mm, has an angular velocity w = 50 rad/s when it is brought into contact with an identical cylinder B which is at rest. The coefficient of kinetic friction at the contact point D is uk. After a period of slipping, the cylinders...
  30. M

    I Velocity Addition: Angled Motion Explained

    Any ideas?
  31. Manasan3010

    Impossible Relative Velocity Values

    The answers were 1) 150 km/h 2) 200 km/h 3 )500 km/h 4) 700 km/h 5) 800 km/h (Chosen Solution) I know that values 700km/h ,100km/h ,-100km/h are possible scenarios but in what ways are 150km/h ,200km/h and 500km/h possible ?
  32. R

    I Unknown velocity vector of a rail carraige

    referring to the image in fig 1 there is a rail carriage subject to an unknown velocity vector Vu (velocity unknown). Vu has a constant velocity Vu in the direction as shown. In the ceiling of the carriage is a light shown in blue and a columnator on the floor. The rail carriage is sitting on...
  33. J

    How to Solve a Doppler Effect Problem with a Moving Vehicle and Siren at Rest

    Pretending the siren is at rest in air: Wavelength = velocity/frequence --> (343 m/s) / 10,000 Hz = .0343m. I don't believe this is the correct way to go about solving the problem, since the vehicle is moving at the start and the siren is not at rest.
  34. M

    How to determine the velocity of a gust of air caused by a falling object

    Summary: I am looking to determine the velocity of a the gust of air normal to a falling object. Say if you to be standing next to an open frame building with a flat roof then take away all the columns and let the roof free fall. What kind of wind velocity would you experience. I am looking to...
  35. msfd

    Question regarding this Basketball Kinematics Diagram

  36. Physics lover

    Velocity after t seconds with a time varying Force

    Figure given in question-: I first found out the time when force will be equal ro friction.After force becomes equal to friction there will be no acceleartion further,so velocity after that time will be same.I calculated the velocity by getting a relation of it with time.I got the velocity as...
  37. G

    I Hubble's Law and Star Velocity

    Hubble's Law and Star Velocity By using Hubble's law and the principle of velocity superposition of relativity, we can deduce when the distance of star from the observation point is (photometric distance)r, its velocity V can be expressed as: V = Csin (Hr/C) Therefore, the...
  38. C

    I Accelerator Particles: Speed of Light & Mass Increase

    In an accelerator when you're pushing/pulling a charged particle with a field that travels at the speed of light why should we expect to the particle to exceed the speed of light.
  39. andrea1313

    I What is the Maximal Parallel Velocity of a Satellite in an Elliptical Orbit?

    so I have this problem from olympiad the maximum value of the satellite velocity component parallel to the high axis of the ellipse(a) and the answer should be vmax=a/b*sqrt(G*M/a). How to prove this?
  40. J

    Inclined Plane, Centripetal motion: Find the Velocity that suits the Turn

    So here is what is going on in my mind: We have a turn that is 400m away from the center of the turn. The faster the car goes, the harder it is for it to maintain its radius. We have a component of the normal force that points towards the center, and static friction which does the same. I...
  41. e2m2a

    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...
  42. Shivam

    Find Velocity of the wooden block at t=4 sec

    Here's the given F-t graph My Attempt... Fsmax=10N & Fk= 5N I made equatiom F=5t-5 ( by seeing Force force and Counteracting kinetic friction) reduced the formula to a=(5t-t)/2 wrote a=dv/dt and solved it but got wrong answer.
  43. A

    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...
  44. nuuskur

    Effects of velocity on weight (mass?)

    A ballistics-esque question. Suppose we are driving at ##x \text{ m/s}## and we have to suddenly brake. For students in driving schools they are told something along the lines of "during the braking, the body experiences ##y \text{ kg}## of force" or "the mass of the body is much higher than at...
  45. pobro44

    Two body problem, velocities of two bodies, relative velocity given

    When only force acting on body is a central force, angular momentum is constant and given by: L = mr^2 * w where r is distance from origin, and w is angular velocity. Angular momentum can also be written as following: L = r x mv = rmv * sin(theta) where v is tangential velocity, which is...
  46. V

    Mechanical vibrations: maximum velocity

    So I am almost sure I know how to solve this, just curious about the maximum velocity. Anyway, if you could double check my calculations, here it is. ##T = \frac{t}{n} = \frac{10s}{15} = \frac{2}{3}s## ##\omega = \frac{2\pi}{T} = 2\pi \frac{3}{2} = 3\pi## a). position at ##t = 0.8s##...
  47. A

    Finding the velocity of a skier

    Problem Statement: 1.I'm asked to find the northerly and easterly velocity of kite skier. the skier is moving 25 ms^1 in the N 25degrre E direction. 2. Wind from the west makes the skier accelerate to the east at 2.0ms^1 for 1.8s CAlculate the new velocity. 3. Use the answer from (1) to...
  48. K

    MATLAB Spring mass impact system in Matlab - How to correct it?

    I am new to Simulink and I wanted to start practicing using a spring mass damper system. My first tutorial was this: Later, I wanted to model a spring system where a mass moving at a known velocity hits the spring. The governing equation and a similar modeling method given in the previous...
  49. A

    Motion Along a Straight Line: Calculate velocity of a stream

    Not sure how to go about it
  50. N

    Calculating a velocity formula using air resistance

    Yeah, not sure what to do
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