# Tag Info

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Remember that velocity and acceleration are vectors, they have a magnitude and direction. Speed, on the other hand, is a scalar quantity which only has magnitude. If you are moving (in a car) towards the right and apply the breaks, you are decelerating (slowing down)--your acceleration is directed towards the left while your velocity ("speed" in the ...

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In this acceleration graph, velocity is going down. Remember that in this graph, the slope is acceleration, so the acceleration is negative. Negative acceleration is what some people call acceleration (slowing down). For negative velocity, imagine a number line. Imagine that you go to 1 in one second. Your velocity is 1 m/s. Now imagine going back to ...

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Can you have a zero velocity and nonzero average acceleration? If you by velocity mean instantaneous velocity, then the question makes no sence. The corresponding acceleration will as well be instantaneous (and the answer would be yes.) $$\lim_{\Delta t \to 0}a_{av}=a_{inst}$$ ... unless it is not a requirement that the acceleration is averaged over ...

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Here we are talking about instantaneous velocity. So,its -20 m/s. And the velocity will be always tangent to the circular track. So,it will be 20 m/s in magnitude every second. But the direction will be different so different values in x & y - axes

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The cited diagram depicts but a small part of the motions that occur during a dive. That appears to be an overly simplified diagram of a rather simple springboard dive, a forward 1 1/2 somersault tuck. It's overly simplified because it misses the complex motions a diver undergoes at the start of the dive. There are two mechanisms by which a diver turns ...

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If the speed of light is constant no matter the speed of the source Actually, the speed of light isn't constant. It varies with gravitational potential, see Einstein talking about that here. However in gravity-free space the speed of light is constant. In addition you measure it to be constant regardless of your motion through space. That's because of the ...

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It does not matter what your velocity is relative to a photon - the photon will always move at a fixed speed from your point of view. This is the 2nd postulate of special relativity - the speed of light in a vacuum has the same value (it's invariant) for all non-accelerating observers (in a medium of uniform density, the speed would be different from its ...

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Einstein's postulate is that the relative speed between the observer and the source does not affect the speed the observer sees the photon moving, as long as the observer isn't accelerating, that is. This basically means there is no such thing as absolute 0 speed. Speed of light is your new and only constant friend.

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If you're both going at a constant speed, lets say 35 MPH, then it would appear so. This is because the distance is shorter in the inner arc in which you are traveling compared to the outer arc in which the other vehicle is traveling.

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Laser Doppler velocimetry can be used. Generally it is used to measure velocity of this range for any transparent fluid flow.

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Terminal velocity of a free falling object is obtained at the moment its acceleration vanishes $$\Sigma\mathbf{F}=0.$$ The forces that act on the object while falling are the gravity force, $$F_g=-mg,$$ and the drag force $$F_d=\frac{1}{2}v_t^2dC_dA$$ where $v_t$ is the ...

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The rate at which the wheel is spinning is an angular velocity, normally measured in radians/second. The velocity of the cart is a linear velocity - metres/second in SI units. Since the two are different units, they can't really be compared. However, you can calculate the instantaneous velocity of any given part of the wheel rim. Unless the wheels are ...

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This can be understood in terms of vector differentiation and the dot product. Take the example that $v \perp r$. The change in the square of the displacement is $$\frac{d}{dt}r^2$$ $$=2r \cdot v$$, and if they are perpendicular, the dot product is zero.

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It takes about 45 minutes for a low Earth circular orbit to go from one side of the Earth to the other say From New York, USA to Perth Australia. If a hole could be tunneled through a uniform density Earth and you were to jump in the hole gravity would act like a spring and it would take you about 45 minutes, (if no air or frictional resistance) to "fall" ...

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