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  2. Speed - Wikipedia

    en.wikipedia.org/wiki/Speed

    Speed is the magnitude of velocity (a vector), which indicates additionally the direction of motion. 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).

  3. Velocity - Wikipedia

    en.wikipedia.org/wiki/Velocity

    Speed, the scalar magnitude of a velocity vector, denotes only how fast an object is moving, while velocity indicates both an object's speed and direction. [3] [4] [5] To have a constant velocity, an object must have a constant speed in a constant direction. Constant direction constrains the object to motion in a straight path thus, a constant ...

  4. Kinematics - Wikipedia

    en.wikipedia.org/wiki/Kinematics

    Angular velocity: the angular velocity ω is the rate at which the angular position θ changes with respect to time t: = The angular velocity is represented in Figure 1 by a vector Ω pointing along the axis of rotation with magnitude ω and sense determined by the direction of rotation as given by the right-hand rule.

  5. Speeds and feeds - Wikipedia

    en.wikipedia.org/wiki/Speeds_and_feeds

    Cutting speed (also called surface speed or simply speed) is the speed difference (relative velocity) between the cutting tool and the surface of the workpiece it is operating on. It is expressed in units of distance across the workpiece surface per unit of time, typically surface feet per minute (sfm) or meters per minute (m/min). [ 1 ]

  6. Group velocity - Wikipedia

    en.wikipedia.org/wiki/Group_velocity

    The ratio between the speed of light c and the phase velocity v p is known as the refractive index, n = c / v p = ck / ω. In this way, we can obtain another form for group velocity for electromagnetics. Writing n = n(ω), a quick way to derive this form is to observe

  7. Linear motion - Wikipedia

    en.wikipedia.org/wiki/Linear_motion

    Velocity refers to a displacement in one direction with respect to an interval of time. It is defined as the rate of change of displacement over change in time. [7] Velocity is a vector quantity, representing a direction and a magnitude of movement. The magnitude of a velocity is called speed.

  8. Streamlines, streaklines, and pathlines - Wikipedia

    en.wikipedia.org/wiki/Streamlines,_streaklines...

    In steady flow (when the velocity vector-field does not change with time), the streamlines, pathlines, and streaklines coincide. This is because when a particle on a streamline reaches a point, a 0 {\displaystyle a_{0}} , further on that streamline the equations governing the flow will send it in a certain direction x → {\displaystyle {\vec ...

  9. Circular motion - Wikipedia

    en.wikipedia.org/wiki/Circular_motion

    Because speed is constant, the velocity vectors on the right sweep out a circle as time advances. For a swept angle dθ = ω dt the change in v is a vector at right angles to v and of magnitude v dθ , which in turn means that the magnitude of the acceleration is given by a c = v d θ d t = v ω = v 2 r {\displaystyle a_{c}=v{\frac {d\theta ...