The time rate of change of the position of an object

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31 views

How to calculate the final velocity of object with variable acceleration?

Initially, an object has a velocity of 0 m/s and acceleration 8.44 m/s2. After traveling 500 km, its acceleration is 9.81 m/s2. How would you calculate the final velocity of the object?
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1answer
42 views

Decreased velocity away from gravity

Say I have a particle ($G$), which has the mass of the earth (hypothetically), and I have a second particle ($P$) moving away from $G$, in a line that is not parallel to the earth. Would this line ...
37
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4answers
5k views

Can water falling from a tap follow a spiral path?

The faucet design depicted below is driving me crazy. The water falling from the tap appears to follow a spiral path. No one seems to agree whether it is physically possible for the water to spin in ...
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1answer
95 views

When is an object at rest?

When is an object considered to be at rest?
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2answers
75 views

$V_{\rm ball}=V_{\rm train}+V_{\rm ball}$?

30 years after reading Einstein's books I'm having another go at understanding astrophysics, but one thing I didn't understand back then still doesn't make sense to me. It is the example of a ball ...
-2
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1answer
111 views

Is there a difference between velocity and drift velocity? [closed]

While I do know that VELOCITY is displacement in time ,I read something about the DRIFT VELOCITY of electrons. What is DRIFT VELOCITY?
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1answer
69 views

Special relativity: can the velocity of a free object be discontinuous relative to an accelerated observer who stops accelerating?

Suppose an observer ${\it {\mathcal O}}$ leaves point O*, origin of the Minkowski frame K*, in the $O^{*}x^{*} $ direction, with a uniform acceleration $a_{0} $ (as measured by himself) ...
1
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0answers
29 views

Resolving multipath interference when modelling radio wave propagation

I am creating a raytracer to model the propagation of radio waves from a simple router. I am assuming that the rays have a frequency of 2.4GHz and a velocity of the speed of light. The router has an ...
-5
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1answer
52 views

What is the top speed of the SR-72 aircraft? What affects would traveling at this speed have on the human body? [closed]

What is the top speed of the SR-72 aircraft? What affects would traveling at this speed have on the human body?
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2answers
63 views

Pressure-Velocity relation at a point in a flow

How can we relate pressure and velocity at the same point in a fluid flow? Why does pressure decrease with increase in velocity?
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3answers
486 views

Why is the scalar product of four-velocity with itself -1?

My GR book Hartle says the scalar product of four-velocity with itself $-1$? Consider the definition of four velocity $\mathbf{u} = \frac{dx^{\alpha}}{d\tau}$. Suppose I take the scalar product of ...
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3answers
83 views

Position, Velocity And acceleration relations

Today we showed our physics teacher our code for a basic physics engine. He told us that this code snippet is incorrect: ...
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1answer
143 views

Zero velocity and non-zero average acceleration

Can you have a zero velocity and nonzero average acceleration? I am confused with the word "average" here. If the question would be, "Can you have a zero velocity and nonzero acceleration?" my answer ...
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0answers
28 views

Faster than light travel at half speed [duplicate]

Peter and Susan are facing each other in outer space. Both of them ignite their their incredibly powerful jet pack thrusters and accelerated away from each other to just over half the speed of light. ...
0
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1answer
47 views

Can I use $(v_1+v_2)/2$ to find average velocity? [closed]

An object is traveling from a point $M$ to a point $N$ with a velocity $v_1 = 600 \,\rm km/hr$ and comes back with a velocity $v_2 = 400 \,\rm km/hr$. What is the average speed of the object? Can we ...
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1answer
52 views

a question regarding relative velocity

"Consider a gravity-free hall in which an experimenter of mass $50~\text{kg}$ is resting on a $5~\text{kg}$ pillow, $8~\text{ft}$ above the floor of the hall. He pushes the pillow down so that it ...
0
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1answer
60 views

How to calculate the deceleration of two trains moving with the same velocity? [closed]

Two trains travelling on the same track are approaching each other with equal speeds of 40m/s. The drivers of the train begin to decelerate simultaneously when they are just 2km apart. If the ...
1
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1answer
106 views

If a car moves at a certain speed, how fast is its wheel going?

Say in a given instance a car moves with speed $v$ and consider any wheel of the car. How fast is it going? Is it the case that the center of the wheel moves at the same speed as the car i.e. $v$? Why ...
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1answer
41 views

Muzzle Velocity confusion

Does muzzle velocity refer to the velocity of the bullet with respect to ground or the velocity with respect to the gun?
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1answer
33 views

How to calculate objects velocity after ataching to surface with a pole [closed]

How do I calculate object's velocity after it has attached it self to a surface with a stick (by stick I mean it is not a spring or rope, it does not bend)? I need it for the video game I am making. ...
4
votes
1answer
154 views

Longitudinal Waves - how velocity varies with density

The formula for finding the velocity of a longitudinal wave, such as a sound wave, is: $$v = \sqrt{\frac{E}{\rho}}$$ Where $v$ represents the velocity, $E$ represents the elasticity of the medium, and ...
1
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0answers
144 views

One dimensional motion problem [closed]

I kept almost 2 hours trying to solve this problem : Two trains are 150 km apart. Train A moves at 50.0 km/hr towards train B, which moves at 30.0 km/hr toward train A on the same track. How ...
2
votes
1answer
249 views

Calculating the eccentricity of an exoplanet

I'm wondering how to calculate the eccentricity of an exoplanet by its radial velocity vs. phase graph. To clarify my question I will take an exoplanet called WASP-14b 2 as an example ...
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0answers
59 views

Centripetal acceleration for a polyline

This question is also posted on the Mathematics forum. I am not physicist, therefore sorry if my question is a bit primitive. Given a polyline (x and y coordinates) in Cartesian coordinate system, ...
2
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2answers
676 views

Does light have initial velocity? [duplicate]

You are standing still in a vacuum, and you throw a ball that moves 10 m/s away from you. Now you start moving in one direction at 5 m/s, and throw the ball in the other direction, away from the ...
2
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1answer
70 views

Why are heat-shields on re-entry vehicles smooth and not textured to increase drag?

Meteorites naturally texture themselves via the formation of regmaglypts, 'thumbprint-shaped' indentations caused by ablation of their surface, during entry into the atmosphere. This appears to ...
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2answers
66 views

Can we say that the instantaneous velocity of an object is the displacement in zero time?

Can we say that the instantaneous velocity of an object is the displacement in zero time? In the image above the instantaneous velocity of the object as change in time gets closer and closer to ...
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2answers
142 views

Rate of deceleration for an average speed [closed]

I'm trying to figure out how to answer this problem: A car is driving at 11 m/s, when it begins to brake. Over the next 25 meters, it averages 6 m/s. At what rate does the car decelerate? Assume a ...
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2answers
79 views

Does a reflecting object move faster than one that does not reflect?

Suppose you have two objects with the same mass and shape, such as a ball, and the only difference between the two is that one reflects light and the other does not. Would one object's velocity be ...
1
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1answer
88 views

If wave speed is dependent on medium only, then how to reconcile $v\propto f$?

I have read and learnt in many places that velocity of a wave depends only on the medium through which it travels. It is clear from this that the velocity of a wave doesn't depend on the frequency of ...
0
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1answer
76 views

Kinematics equations of motion find x position in 2D from height

I have a question and I thought of 2 possible ways to answer it however the resulting answers are different which means I must be doing something wrong in my calculations. All the below happens 2 ...
1
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4answers
106 views

Special Relativity - travelling close to light speed

When we say something travels close to the speed of light, what is its speed relative to? For example, we have 4 highly advanced spacecraft at rest beside each other, labelled A, B, C and D. We ...
0
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2answers
93 views

Solving distance with acceleration and velocity given and getting two different answers using two different equations [closed]

Frictional forces from brake pads are responsible for stopping an automobile. A car is moving at $35.0 \:\mathrm{m/s}$. If the car's brakes are capable of generating a deceleration rate of $6.00 ...
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1answer
415 views

Is instantaneous velocity a scalar or a vector?

So this is a simple question that I have been confused about. Last night I was in a discussion with a friend, and we somehow ended up on this topic. He believes that instantaneous velocity is a ...
0
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1answer
1k views

How to calculate speed and distance from gyro, orientation and acceleration data?

In iOS 8 SDK, there's an API that gives you a distance covered by user over a period of time. I wonder how is Apple calculating distance, as it seems to work without GPS help. And since I have the ...
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5answers
186 views

Why are position and velocity enough for prediction and acceleration is unnecessary?

In classical mechanics, if you take a snapshot and get the momentary positions and velocities of all particles in a system, you can derive all past and future paths of the particles. It doesn't seem ...
2
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0answers
38 views

Can a projectile moving at supersonic velocities leave a silhouette in whatever it hits?

I was recently reading this, and Floris's answer confirmed my knowledge that the information of an collision travels at the speed of sound. While I was thinking about that, my mind wandered and I ...
4
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8answers
588 views

Can velocity be an undefined quantity?

We have the image below displaying the uniform velocity by time-distance graph. At every point velocity is constant but what if distance and time both become zero as at origin in the graph is? The ...
1
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4answers
477 views

Why don't we take force proportional to velocity? [duplicate]

When a Force is applied on a body at rest, it produces Acceleration which is equal to change in Velocity. But due to the Force, we see that the Velocity is increasing consequently. So why don't we ...
1
vote
1answer
905 views

Calculate speed from accelerometer

I am trying to use my accelerometer on my mobile device (smart watch to be specific) to calculate a persons arm swing speed. The data returned from the accelerometer is in $m/s^2$. Since the ...
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2answers
102 views

Factors on which Coefficient of restitution depend

What are the factors on which coefficient of restitution depend? What is the reason for more coefficient of restitution of two glass balls (0.95) than for two lead balls (0.20)?
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2answers
45 views

Does juggling faster less work then juggling slower?

I got this idea when juggling. Let's say three balls with the standard technique. When I throw the balls higher it is harder (more work), but since it takes more time for them to fall back I work less ...
0
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3answers
80 views

Does there exist a hyperbolic relationship between frequency $\omega$ and wavenumber $k$?

As the title states, is it possible to derive a hyperbolic relationship in the form of $\frac{x^2}{a^2} - \frac{y^2}{b^2} = 1$ between frequency $\omega$ and wavenumber $k$ I have tried to start this ...
0
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2answers
97 views

Playing catch in space?

I was thinking about this on the bus (exam this week :P). What would happen if two people played catch in outer space? Lets say person A and B are in space at rest, A throws a mass m at B, what ...
0
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1answer
53 views

Are velocity and accelerate smooth quantities?

My thinking: acceleration corresponds to a force which is instantaneous, so the acceleration of a rigid body can be rather spiky (non-smooth) velocity (angular velocity) describes the ratio of ...
0
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1answer
99 views

Is velocity always tangential to trajectory?

So I was doing an exercise and they find find the angle between the tangential of trajectory and the vertical I was stuck but then I read in a site that the velocity is ALWAYS tangential to the ...
0
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0answers
19 views

Overall Velocity of Body with Multiple Wheels

Let's say you have some object, a car or whatever, that has multiple wheels going in multiple directions, each of which can spin at different speeds. How would one go about getting the overall ...
14
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3answers
361 views

When passed, why does my car 'rock' on the highway when I'm stopped, but not when I'm moving?

I am the blue car in this scenario. If I am stopped on the highway and am passed by a car going fast (about 65 mph), I feel my car rock in the left/right direction. I think I understand why this ...
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0answers
28 views

Particle Velocity and Air Velocity

Is the any relationship (equation) between particle velocity and air velocity? Is it possible to determine the air velocity from particle velocity?
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1answer
55 views

Air Presure and Air Velocity from speaker

How do I determine/calculate the air pressure emitted from a speaker ? And how to determine the velocity of air from the sound air pressure ?