The time rate of change of the position of an object

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1answer
88 views

If velocity for an interval is zero then is acceleration also zero throughout?

We know that if velocity is zero for an instant, then acceleration need not be zero (a simple example of which is a ball thrown upwards.) But if velocity is zero for an interval, will ...
1
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1answer
160 views

How do I graph acceleration?

I have written some java code for the calculation of some various acceleration and etc. type data. I am now trying to graph that data so I can pull specific data over a time line. The values I have ...
0
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0answers
41 views

Bezier curve and deceleration

I have a question regarding calculation of a bezier curve. I'm programming an app where in there's continuous straight line motion of a vehicle at a constant speed. (Let's call it 'u'). When the user ...
2
votes
4answers
506 views

Are wavelength and the distance same thing?

Can you clarify for me the following question: are wavelength and distance same? I know wavelength is measured in terms of distance but when we have a look at the two equations: $$ c=f\,\lambda\\ ...
1
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1answer
383 views

How are the higher derivatives (jerk, jounce) of position with respect to time used in physics?

I don't see them much in any physics lesson or course, but that's probably because I'm not into physics as much. I can understand why velocity and acceleration are useful, but why would someone want ...
0
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1answer
28 views

Rate of movement at an RFID reader

I'm working at using RFID readers to track movement. It's for a computer science project. I haven't done physics in a long time. I'm using passive RFID tags. This paper ...
2
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3answers
519 views

Basic question about acceleration [duplicate]

Very basic question. Please show where I'm wrong in the following reasoning. The movement of an object in function of time could be described as $$ x(t) = v t + x_{i} $$ if velocity is constant. If ...
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2answers
1k views

Why can velocity and acceleration be negative?

Why is speed and acceleration negative when $V_1$ of an object is say 150m/s, $V_2$ is 0 m/s and $\Delta d=0.50\,\rm m$? I found the time it takes which is 0.0033s and the acceleration to be 90909.09 ...
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0answers
149 views

Travelling at a relative speed greater than the speed of light [duplicate]

I've wondered about this since I was a kid. I've been told the speed of light is a constant ($c$), which would mean that light always travels at the same velocity. Now, here's what interests me: if ...
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1answer
89 views

Velocity of a car in circular circuit [closed]

Prior apology for any violation of rules and regulation and poor expression of question. Statement: A racing car moves along a circular circuit with a constant speed of $20\text{ms}^{-1}$ in 5 ...
1
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1answer
467 views

Why does a diver changes his body positions before and after diving?

Before a diver dives in a pool, he changes his body positions several times. When he is about to jump from board he extends his arms and legs but sometime after jumping he closes his body in a ...
0
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3answers
133 views

Our speed and direction by comparing the speed of light?

If the speed of light is constant no matter the speed of the source, shouldn't we be able to know the direction and exact speed we are going relative to the absolute 0 in speed? If a photon is sent in ...
3
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1answer
74 views

Why do you seem to go faster as you hug a turn?

I was driving to work this morning when this question occurred to me. I was going up a clover-leaf entrance ramp to the highway. The person in front of me was lazily floating the outside of the curve, ...
0
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1answer
44 views

What would you do to measure wind speed below 50m?

Is there a radiation spectrum that could be used near the surface of the earth to fluoresce air enough to see the currents? Is there a complimentary CCD that can image that spectrum? I am looking for ...
2
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0answers
53 views

Deceleration of spherical particle in fluid

If I know the initial velocity of a particle entering a fluid, how can I calculate its deceleration over time ? What parameters would I need to know ? Viscosity of the fluid, weight of the particle ...
1
vote
1answer
102 views

Is there a speed limit for objects falling in gases or liquids? [duplicate]

Let $o$ be a spherical object with mass $m$ and surface $s$. Let $g$ be the gravitational acceleration and $h$ the height. Let the gas where we drop $o$ in have density $d$ and pressure $p$ at ...
0
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1answer
87 views

Cart speed and wheel rotation

Say you have a horse drawn cart. Does the outside of the wheel spin at the same velocity that the cart moves forward? The reason I ask is because I am working on a problem where a piece of mud ...
0
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1answer
96 views

Why is parallel component of velocity along position vector considered rate of change of position?

If you have a position vector and a velocity vector of a particle, then the component of velocity vector along position vector is the rate of change of distance of the particle from the reference ...
1
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1answer
100 views

How are the theoretical properties of a gravity train linked to orbital properties?

Whilst perusing a question on WorldBuilding, a link was given to an article about Gravity Trains. Some of the answers on the question, and the Wikipedia article, state a travel time of 42 minutes ...
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1answer
436 views

How to derive velocity pressure in English units?

I know that velocity pressure can be calculated from dynamic pressure according to the potential energy of pressure (from Bernoulli's equation): $$ P = \frac{1}{2} \rho \overline{V}^2 $$ where P = ...
30
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5answers
4k views

Why don't things get destroyed by gas molecules flying around?

Gas molecules go at an insane velocity, and though they are miniscule, yet there is a LOT of them. Of course, because of all these molecules hurtling around, there is air pressure; yet if you envision ...
0
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2answers
47 views

What theories or formulas are involved with velocity

What theories or formulas are involved or can be added as background information in an experiment that sees a small toy car roll freely down an incline where the surface area is altered to cause more ...
0
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2answers
85 views

Movement of accelerating points with maximum speed (i.e. running away from tiger) [closed]

I'm walking through a forest and suddenly I see a tiger. And now I have a problem. I want to know how much time I have left but I don't know how to calculate it. Or more formally: Let's ...
0
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1answer
2k views

What factors affect the velocity of an object moving down an inclined plane?

If you have a small toy car rolling down an wooden plank, what factors would increase or decrease the velocity of said car. In the experiment my team originally stated that adding mass to the car ...
1
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1answer
130 views

What causes angular and linear deceleration in a sliding and rotating ring?

I was solving an AP Physics problem involving a ring sliding and rotating over a frictional surface. When I started to think about why the ring eventually comes to a stop I started to become confused. ...
0
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2answers
48 views

How can velocity be measured on a persons hand?

How can Velocity of a hand be measured for example i have my hand flat bent backward like holding a tray, i want to measure the initial speed of my hand as motion begins when i flick my hand
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2answers
121 views

In special relativity, is it correct to say the speed of a body B relative to A is the same as measured by every observer?

Here, two objects A and B are moving relative to each other. I use the Einstein velocity addition formula $v = {v_1 + v_2\over 1 + {v_1 v_2\over c^2}}$ to calculate the relative speed between A and ...
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3answers
98 views

Why is there a contradiction in this Newton's equations of motion related question? [closed]

One second after being thrown straight down, an object is falling with a speed of 20 m/s. How much distance does the object travel in the first second? We took: $$v = 20\,{\rm m/s}$$ $$u = 0\,{\rm ...
1
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2answers
709 views

Average acceleration versus instantaneous acceleration

Does instantaneous acceleration also changes when direction of velocity changes. I know average acceleration does change.
1
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1answer
1k views

Difference between Speed and Velocity

What is the difference between Speed, Velocity and Acceleration? Could any one describe it pictorially?. I am more over confused even after investigating many times. I am unable to relate myself ...
-2
votes
1answer
159 views

Find the average speed and velocity of the object [closed]

An object travels 11 m north and then turns around and travels 25 m south. If the total time of travel is 52 s what is the average speed and velocity of the object. I used the formula I was told ...
-1
votes
1answer
173 views

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 [closed]

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 At what point should the particle be released to hit a target of (2,0,0)? ...
0
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1answer
401 views

Representation Of Linear Velocity as Cross Product

Why is linear velocity represented as cross product of angular velocity of the particle and its position vector? Why not vice versa? (Consider rigid body rotation)
0
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1answer
44 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 ...
38
votes
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 ...
-1
votes
1answer
936 views

When is an object at rest?

When is an object considered to be at rest?
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2answers
84 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
votes
1answer
459 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?
1
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1answer
107 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
49 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
votes
1answer
70 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
146 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?
4
votes
3answers
626 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
230 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: ...
1
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1answer
952 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 ...
0
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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
votes
1answer
55 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 ...
0
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1answer
74 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
votes
1answer
116 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
vote
1answer
206 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 ...