# Questions tagged [velocity]

The time rate of change of the position of an object

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### Tangential Velocity of a Wheel Connected to a Rigid Link While Passing the Ramp [closed]

As seen in the figure, the rigid link moves at constant velocity (V) on the x-axis. This rigid link is connected to the tractor on the x-axis from one end and to the wheel from the other end with ...
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### Coriolis force relation to wind velocity

I'm learning coriolis effect on Winds moving from equator towards North pole. This is for geography. Question: Why is coriolis force stronger for winds having larger speed(larger component of ...
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### In a uniformly accelerated motion experiment, the acceleration can be attained from $V_{ave}$ vs. $t/2$ and $x$ vs. $t^2$ graph. How is this possible?

Specifically, in the experiment, we had to release a glider from an inclined plane (that had an angle of inclination of 10 degrees). We had to calculate the time it reaches the final position. We had ...
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### Why does force perpendicular to the velocity change only its direction; not the speed?

While analyzing the case of a force and consequently an acceleration acting perpendicular to the velocity of a given body, I do understand that force's component along the velocity will be 0 causing ...
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### Definition of four-velocity: why define it with proper time of the object?

The four-velocity(world-velocty) is defined by : $u^μ=\frac{dx^μ}{dτ}$ ,where $τ$ is the proper time of the object. I don't understand why it's defined with respect to the proper time but not the time ...
1 vote
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### Calculating linear velocity based on the (Euler) rotation matrix having 2 time indices

Normally, we denote a rotation matrix with respect to time as $R(t)$. As I understand, we can only denote like that because the initial observation is assumed to be zero ($t_0 = 0$) and $t$ is ...
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### Product of two 4 positions without writing the components

I was able to solve the first part of the following question by expanding the terms as vectors I can't understand how to do it without expanding so I had a look at the answers. I understand how we ...
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### Relative velocity motion in this case

Take a look at this picture, the point $a$ is the location of the wheel's center in the robot's frame {$0$}. The point $c$ is attached to a robot's mass center. The angular velocity $\omega$ is the ...
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### Why don't boundary layers have a transverse pressure gradient due to the Bernoulli effect?

This is something I always thought about but never truly understood. A boundary layer has a velocity gradient, $\partial u/ \partial y$. The Bernoulli principle states that pressure and velocity are ...
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### Question about the norm of the four-velocity being equal to $c$

On the way to the Einstein equation we derived the four-velocity: $$u^\mu=(c,v^k)$$ with $v^k$ being the 3-velocity, which can can be very low ($|v|<<c$). However, the square of the four ...
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### Can generalised momentum be defined as mass times generalised velocity？ [closed]

The generalised momentum is defined by the partial derivative of Lagrangian. Can we think of this as a mass times a generalised velocity?
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### Wording of Relative Velocity problems [closed]

I've been doing some relative velocity problems. The three main types I do are to do with cars, boats/rivers and planes/crosswind. I'm fine with cars as the wording is pretty straightforward - it is ...
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### Centripetal acceleration with constant speed

If a particle is moving in a circular path at a constant speed, how can we represent its centripetal acceleration? Since the speed is constant, I assume that the centripetal acceleration describes how ...
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### Position-time graph of two cars is given [closed]

So this was a test question, I answered that both cars have the same acceleration. Since the graphs for A and B both are straight lines, therefore, the acceleration of both must be zero. But the ...
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### Where to find the article(s) saying that 3D Navier-Stokes solutions exist in case of a small initial velocity?

I've already been searching for here and on the internet, maybe not enough. PS: this result is stated in the Clay Mathematics Institute N-S problem definition, page 2: https://www.claymath.org/wp-...
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### Collision Calculation in 2D

For a 2D physics simulation, I need to resolve collisions between two objects in 2D. I have available each object's initial angular velocity, linear velocity, mass, moment of inertia, and center of ...
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### Shouldn't acceleration of a car be due to kinetic friction? [closed]

During pure rolling when the car is at a constant velocity the velocity of the bottom part of the tire will be 0. But if we push on the gas we apply an angular acceleration on the tire. So now the ...
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### Doubt in displacement time graph for a body moving with constant, negative velocity

This is a displacement - time graph of a body having constant, negative velocity. As we can see, the angle $θ$ (in anti - clockwise direction) is greater than $270^\circ$, and lesser than $360^\circ$,...
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### Average angular velocity and speed

Are the magnitude of average angular velocity and the value of the average angular speed always same? If not then can you please give an example.
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### When a person falling reachs terminal velocity, the body moves in a constant velocity. But shouldn't the body not move bcs there are equal forces?

Why is the person not staying stationary in the air when there is equal forces from both sides?
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### How Long For An Object To Catch Up To Another Object Moving At Different Speeds? [closed]

Example: A bear is 10 m away from a person, the bear is moving at a speed of 15 m/s, the person is moving at a speed of 6 m/s, how long would it take for the bear to catch up to the person? I'm not ...
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### How can the equation for generalized force be derived assuming the system is in equilibrium?

I have been going over sections 1.4-1.5 of Goldstein's Classical Mechanics where the equation for generalized force Q_j=-\frac{\partial U}{\partial q_j} +\frac{d}{dt}\frac{\partial U}{...