The time rate of change of the position of an object

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0
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2answers
116 views

stopping a rotating mass to achieve linear velocity

So I've been thinking about space, and I had this idea. I haven't found any prior art online for it, and from my limited understanding it seems like a viable idea. So I guess my question is, what am I ...
-1
votes
1answer
35 views

Calculate the distance of a falling object and terminal speed [closed]

I have a homework problem that I would like to verify that I am doing it correctly. If anyone could help me see where I'm going wrong with the steps, I would really appreciate it. (a) Consider a ...
0
votes
1answer
62 views

For a particle moving in a circle,can $a_t\neq 0$ and $a_r= 0$? [duplicate]

I know for a fact that if a particle is moving in a circle such that the value of radial acceleration is non-zero and the value of tangential acceleration is zero ,then it can be classified as ...
0
votes
1answer
53 views

Differential equation for velocity regarded as a function of distance [closed]

Given a differential equation for velocity, $dv/dt + v = 1$, as well as its solution, is it possible to derive a differential equation for velocity with respect to distance? I found a solution to the ...
1
vote
2answers
192 views

How to find the height at which a projectile is launched from an angle? [closed]

I need guidance with the following question: A boat is $50.0m$ from the base of a cliff, fleeing at $5.00m/s$. A gun mounted on the edge of the cliff fires a shell at $40.0m/s$ and hits the boat ...
0
votes
1answer
36 views

magnetic field strength paradox-where is my error in reasoning?

Under the assumption that I understood the following circumstances correct: Magnetism occurs when a charged particle moves with a certain velocity through space. Faster velocity equals a stronger ...
2
votes
2answers
82 views

What is meant by the velocity of a star?

I recently read somewhere that among other things like size, radius, distance from earth, luminosity, age, etc of a star, velocity was another variable. What is exactly meant by the velocity of a ...
1
vote
1answer
34 views

Speed of different inclined plane [closed]

Assume friction-less, an object was release from the top, what is its speed at the lower end of the slope? I tried $v= \sqrt {2*9.0m/s^2*5m}$, but I doubt if it's a correct answer, any help?
-1
votes
6answers
274 views

What is the acceleration at the top most point of a ball’s journey vertically upward?

When i shoot a ball vertically upward, it’s velocity is decreasing. So there is acceleration. -9.8m/s^2. I’ve read that at the top most point, the acceleration is STILL 9.8 m/s^2 where v=0 . The ...
0
votes
3answers
136 views

Deceleration of a bullet [closed]

Taking into account gravity, air resistance, and wind velocity and direction. (And also temperature if it's actually relevant.) I know the muzzle velocity, the total distance the bullet traveled, its ...
6
votes
3answers
873 views

Does an ion thrust engine consume more energy as it speeds up?

This question goes to a very basic non-understanding of mine that I have had in the back of my mind for ages - I just read the following here: ion thrusters are capable of propelling a spacecraft ...
0
votes
2answers
79 views

Velocity of photon when changing direction [duplicate]

We know the speed of a photon is constant. Yet when any other object changes direction, its velocity must go to zero. Thus, my question is how does a photon avoid this? I assume that to change ...
0
votes
2answers
79 views

Calculating Acceleration

I'm having problems calculating acceleration for the following variables. I would have thought it would be extremely straight forward, except I am getting two different answers and do not know which ...
0
votes
1answer
49 views

Why the point right below the center of a rolling ball on the ball has zero instantaneous velocity [duplicate]

Suppose there is a snooker ball rolling on a table. The velocity of the center of the ball is Rω and its direction is horizontally right. I don't understand why the point right below the center on the ...
3
votes
4answers
2k views

Does a moving object curve space-time as its velocity increases?

We always hear how gravity bends space-time; why shouldn't velocity? Consider a spaceship traveling through space at a reasonable fraction of the speed of light. If this spaceship, according to ...
0
votes
1answer
42 views

What is the change in velocity? [closed]

A boat moves with a velocity of 22 m/s directly west. Later, the boat is found to have a velocity of 12 m/s at 45° S of W. What is the change of velocity? I want to do this vector wise. I know that ...
0
votes
3answers
68 views

Finding velocity from distance and gravity

Basically, I have a problem that asks: An object is launched to a height of 2 miles, what was it's initial speed and time. Now normally something like this would be fairly basic. The problem ...
-1
votes
4answers
168 views

Meaning of fourth component of velocity four vector

Can any one help me to understand what the fourth component of velocity four vector mean physically?
8
votes
5answers
2k views

How to brake 'beautifully'?

Sometimes when I'm driving my car, I play a "game" against myself in which I try to minimize the deceleration felt by passengers (including myself) while still braking in a reasonable short space. I ...
0
votes
2answers
97 views

Kinematics with acceleration as a function of velocity

Say there is a particle moving at $50~\text{m/s}$ and modeled with a function of acceleration such that: $$a = - 0.5v$$ (this is derived from a force as a function of velocity) $$F = 50v = ...
-1
votes
2answers
61 views

1D Kinematics problem [closed]

The position of a particle in meters moving along the x-axis is given by: $x = 3(t − 2)^2 − 12$ for $0 \le t \le 15$ How can I find the velocity of the particle when it is passing through the point ...
1
vote
1answer
109 views

How does the angle between two objects change relative velocity?

I apologize in advance if my question isn't clear. If two objects start from the same position, but leave in opposite directions--say $40^0$ west of north, and $50^0$ east of north--how would an ...
-1
votes
1answer
111 views

Mass of a particle ( relativity)

A hypothetical atom has a rest mass of $15.000000136\,\mathrm{u}$. Overtime it undergoes a spontaneous breakdown into two masses of $7.000000229\,\mathrm{u}$ and $6.902727019\,\mathrm{u}$ ...
0
votes
2answers
289 views

Finding acceleration and distance when velocity given

I am trying to do the following question for practice (it is an interview question), and I don't know if my methods and answer are correct. Given a velocity $v=2+3t^2$, find acceleration after 3 ...
-3
votes
1answer
33 views

Calculating Changes in Velocity [closed]

When $+6.0$ m$\cdot$s$^{-1}$ becomes $+15$ m$\cdot$s$^{-1}$ is it said to have a change in velocity of $9$ m$\cdot$s$^{-1}$. If so, when a direct velocity such as $+6.0$ m$\cdot$s$^{-1}$ changes to ...
0
votes
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 ...
0
votes
0answers
17 views

Issues determining velocity in a totally elastic collision

A block of mass $M_1$ is attached by string to a support. The block is raised to a height and released. It then strikes a block of mass $M_2$ on a frictionless surface. Find the velocity of block ...
3
votes
5answers
67k views

Finding the force of friction of a moving object and its change when it accelerates to a constant speed

I have been searching for a straight forward answer to this question for ages now and it is driving me crazy. Here is what I know: If an object is moving at a constant speed the force of friction ...
-1
votes
4answers
250 views

Position from a Velocity-Time graph

Find the position at t= 3.0 seconds. The initial position is 2.3 m. I found the average velocity to be 3.33 repeating so I multiplied that by the time (3) to get 10 and then added the initial ...
0
votes
2answers
495 views

Vertical Circular motion - Tension and velocity [duplicate]

I read through the question Minimum velocity of the particle at the highest point which is quite similar to my questions. But I still have some doubts in the answers - "The particle will complete ...
0
votes
1answer
70 views

Clarification of the physics involved of an orbiting body in a circular orbit

I am writing a physics simulation program to simulate a body orbiting a planet but I am a little confused about the physics involved and would like some clarification. To simulate gravity I am using ...
1
vote
2answers
145 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?
-2
votes
1answer
97 views

Why do we need displacement? [closed]

In practical life we see objects not actually moving on same way as of displacement,They cover distance. While studying physics why do we study displacement and velocity. Is there any practical use ...
3
votes
2answers
337 views

Intepretation of area under velocity-time graph for a bouncing ball

A typical velocity-time graph for a bouncing ball is shown below. I understand that the ball starts from rest at $t=0$, then it accelerates downwards and hits the floor at time $t_1$. Between time ...
1
vote
2answers
41 views

Projectile motion velocity [closed]

If a projectile breaks into two pieces at the highest point of its trajectory and one of them retraces the same path, why will that piece have the same magnitude in velocity as the whole projectile?
2
votes
2answers
79 views

Derive the velocity-additon formula from the Lorentz transformation

In a Euclidian world the sum $s$ of two velocities $v$ and $u$ is so such that $s = v + u$. However, in the world of special relativity that's not the case. Instead, the velcity vector sum $s$ is ...
0
votes
3answers
243 views

Rate of Acceleration of an Object Pulled by Magnetic Force

Gravity on earth pulls objects toward it with an acceleration of 9.8 m/s/s on Earth until the object reaches it's max potential free fall speed. (I call this terminal velocity though I think that this ...
5
votes
4answers
584 views

Why does objects with zero acceleraton move?

My question is, if we apply a force on an object to move it with a constant velocity, of course it will move. But what I don't understand is, why will it move? From Newton's law F=ma and in this case ...
1
vote
1answer
61 views

How can we find velocity, acceleration etc, of a revolving particle with respect to an observer inside the circle(not at center)

A particle is revolving in horizontal a circle of radius $R$ with constant speed of $|\vec{v}|$ and constant angular velocity $\omega$. There is another observer standing inside the circle, at a ...
1
vote
3answers
324 views

A question in Special Relativity

In books the equation for length contraction is derived by supposing that the velocity of the spacecraft is the same for both observers. So the question is that, is the velocity really the same for ...
1
vote
2answers
130 views

Is $v$ not always equal to $\omega r$ in angular motion?

NB:I am not asking an answer for the question quoted. I had this question given in my book: A ring of radius $R$ rolls on a horizontal ground with linear speed $v$ and angular speed $\omega ...
1
vote
0answers
104 views

What is the relationship between the velocity of an object and its Sound Intensity Level in an inelastic collision?

Assuming the mass, acceleration, and height of the dropped object are constant and the area of the measured sound wave is constant, would the relation be linear, exponential, logarithmic, square root ...
1
vote
2answers
88 views

Velocity of approach of a beam of light and a moving object

I came across a problem on Brian Greene's course on Special Relativity. (http://www.worldscienceu.com/courses/6/elements/TnRUSU) From George's perspective, how fast does a beam of light approach ...
-2
votes
2answers
88 views

Save a falling person by nullifying their mass or reversing gravity [closed]

Let's say you have the superpowers to manipulate matter, mass and gravity. Imagine a person falls off a plane, flying few kilometers above the air, and they are about to get splattered onto the hard ...
7
votes
6answers
5k views

When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?

Consider these two situations when driving on a long straight road uphill: Starting at a high velocity $v_h$, which the car is able to maintain. Starting at a lower velocity $v_l$, and then trying ...
0
votes
2answers
108 views

Convert an equation for acceleration into one for velocity

A sledge is pushed in a straight line. Assume surface is smooth. When the sledge is x distance away from the start the magnitude of its acceleration is given by $0.08e^{-4x}$ and is going in the same ...
0
votes
2answers
223 views

Orientation of a rocket going in a circle?

This problem is from my physics homework: A rocket is moving at constant speed in a perfect circle in deep space, far away from any planets or stars. The diagram below shows the circle the ship ...
0
votes
3answers
110 views

Difference between $|d{\bf r}|$ and $d|{\bf r}|$

What is the difference between $|d{\bf r}|$ and $d|{\bf r}|$ and why are both of them not always equal to each other? My question might seem stupid to some and will probably get downvoted but I have ...
0
votes
1answer
50 views

Is the car/wall comparison valid for speeds close to $c$? [duplicate]

At school, people commonly think about momentum and conservation of energy using the example of a car collision. A common phrase is "Do not try to think of two objects moving, think of one moving at ...
2
votes
2answers
113 views

Sum according to a function - composition of velocities

An observation more than a question. Take any function $f$ (additional hypotheses may follow) and evaluate it on any two points $x_1, x_2\in\mathcal{D}_f$. Define then the sum of these two points as ...