Questions tagged [velocity]
The time rate of change of the position of an object
1,795
questions
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Question related to Hodograph Kinematics! [closed]
The area of the triangle formed till any time is :
(a)1/2 x horizontal velocity x change in vertical velocity
(b)1/2× g x horizontal displacement
(c)Distance travelled by projectile x g
(d) g² x ...
0
votes
2answers
32 views
Energy of the system after displacement
A massless pulley has two bodies hanging of masses $m_1, m_2$ on both sides. Now $m_1$ moves upward by $h$ meters and $m_2$ moves downward by $h$ meters. What is the velocity of the system after the ...
7
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4answers
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Parallelogram law of vectors
[This is a very silly question. Will be a great help if someone could answer this question]
How is this law proven? I am not asking about the proof itself rather asking about the preliminary ...
-2
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3answers
52 views
A goes left and B goes right with same velocity. What is the velocity of B relative to A? [closed]
According to my analysis velocity of B according to A is 2 times the original velocity.
0
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2answers
50 views
Why is acceleration defined in terms of velocity in this equation?
I am having an issue understanding this mathematical modeling of an electromagnetic braking system.
I have this equation where z is the position and t the time,
$\frac{d^2z}{dt^2} = g - \frac{RL\...
0
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2answers
28 views
Angular and linear velocity of a circle
Let's assume I have a circle of radius $r$ and I apply a constant force at a point on the circumference of the circle that is perpendicular to the distance vector which goes from the centre of the ...
0
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1answer
22 views
Why should we integrate to find displacement instead of directly plugging in $t$ for displacement function?
context:preparing for jee, chapter kinematics. text book problem
given $v = 2t^2$
find $x$ at $t=2s$ if at $t = 1s$, $x= 3m$
My solution
integrating v to find displacement fucntion
$$
x(t) = \int2t^...
0
votes
1answer
18 views
How to calculate kinetic friction coefficient given velocity and height?
The problem I am dealing with is about an object sliding down a ramp. I am only given the height of the top of the ramp to the floor, initial and final velocity, and weight of the object (in lbs). How ...
5
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4answers
514 views
Terminal Velocity and Work
I don't know much yet about energy and work, as I've only had one lesson on it so far. However, our teacher told us that zero work is confusing and that we wouldn't need to know about it (with the ...
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1answer
26 views
Finding the acceleration of a vehicle travelling past three posts [closed]
A vehicle travelling along a straight road with uniform acceleration passes three posts in turn placed at A,B and C, each 50m apart. It takes 6 seconds to pass between posts A and B, and 9 seconds to ...
0
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0answers
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How to determine true wind speed? [closed]
A sailboat is sailing due east at 5.00 mph. The wind appears to blow from the southwest at 14.2 mph. What is the magnitude and direction of true wind speed? what if the wind appears to blow from the ...
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0answers
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Velocity vector transformation from global reference frame to object reference frame
I have two objects in 3D with positions $\vec{^{w}P_{1}}$ and $\vec{^{w} P_{2}}$ moving at velocities $^{w}\vec V_{1}$ and $^{w}\vec V_{2}$. w represent world reference frame. For my question below ...
0
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1answer
32 views
Determine speed of moving vehicle from video taken in a moving vehicle [closed]
I have dash camera footage from my motorcycle where the police were speeding illegally in dangerous conditions. I know my speedo is 7% over so if it reads 107KPH a radar gun will ping me at 100KPH.
I ...
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votes
2answers
68 views
Why do we use $\frac12(v_f+v_i)$ in the kinematic equations?
I find it confusing that we have to use the average of the velocity instead of the final velocity. Can someone explain to me why
$$s = \frac12(v_f+v_i)t$$
is true?
0
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1answer
21 views
Calculating kite surft jump height using acceleration [closed]
I am trying to calculate the height of a kite jump using the accelerometer in a phone. There are two apps already doing this and I want to replicate this behavior.
(The two other apps are Surfr and ...
0
votes
1answer
43 views
What is the difference between $v=fλ$ and maximum velocity in the formula $v=ωY_{\max}$? [closed]
I was wondering what the difference is between speed in the formula $v=fλ$ and maximum velocity in the formula $v=ωY_{\max}$ as applied to a wave.
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2answers
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If Newton’s 3rd law describes a simultaneous force to force reaction then doesn't that imply that force and the resulting velocity are simultaneous? [closed]
When a force is applied to a particle for a duration of time and we observe the velocity at any instant of that duration Newton’s 3rd law tells us that the force and resulting velocity are ...
0
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1answer
38 views
Is Initial velocity of an object zero after it reaches maximum height and starts free falling under 1 dimension?
I am studying motion in 1 dimension in kinematics and doing gravitation part. I was doing a question in which a ball is thrown upward from a tower of height $20\mathrm{m}$ with a speed of $5 \mathrm{m}...
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2answers
86 views
If by calculating a velocity I end up with $v = \sqrt{1}$ [closed]
Do I then take the $-1$ as the answer or the $+1$? I'm asking because in my situation the velocity is going in the opposite direction than what the positive direction was deemed to be. Do I just take ...
0
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0answers
22 views
Calculating $\Delta V_{sound}$ when $\Delta T = 1 K$ when $v_{sound}$ at 273 K = 332 m/s
Here is my solution
We know that $v_{\text{sound wave}} = \sqrt{\frac{\gamma RT}{\rho}}$
which means that $v_{\text{sound wave}}\propto T(\text{in Kelvin})$
$\implies \frac{v_1}{v_2} =\sqrt\frac{T_1}{...
0
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2answers
40 views
This question is about negative velocity
So let's say I have an object moving from the points X to Y and my positive direction is to the right. Now suppose the object moves back from Y to a point W on the line between X and Y. Is the ...
2
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2answers
138 views
Is four-acceleration spacelike? How to show this? What does it mean?
Consider a four-velocity $u_\mu$ that satisfying $u_\mu u^\mu=c^2>0$. Differentiating w.r.t the proper time $\tau$, we get the equality $a_\mu u^\mu=0$ which means the four-velocity and four-...
2
votes
3answers
124 views
Speed $v$ of a wave on a tightrope
Starting from D'Alembert's general wave equation we can find the propagation speed of an impulse along a tightrope as a function of linear mass density,
$$\boxed{v= \sqrt{\frac \tau \mu}} \tag 1$$
...
0
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1answer
21 views
Considering air resistance is the force applied to lift an object equal to its weight? [closed]
Considering air resistance is the force applied to lift an object equal to its weight when the object moves at constant velocity?
0
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1answer
37 views
How can I calculate $z_1$ when the ball is on $y_1$?
I'm developing a clone of Pong game and I don't know how to compute this:
There is a ball moving on axes $Y$ and $Z$. There is also a paddle on $y_1$ which can only move along axis $Z$.
I don't know ...
0
votes
1answer
86 views
Can position be derived from acceleration in practice?
We know that acceleration is the derivative of velocity, and velocity is the derivative of position. But does that mean that we can find position from acceleration in practice (as opposed to in theory ...
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0answers
27 views
How much centrifugal force would it take to create gravity?
If say your car was stuck in the mud. You press the gas the wheel spins and the centrifugal force shoots mud out the back, how fast would the tire need to go to keep the mud perpetuating around it ...
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1answer
39 views
Velocity of an object with respect to the same object
I know that velocity of an object with respect to the same object is a null vector but I'm not able to get a feel of it.
Whatever I had thought till now is that if I'm sitting in a train (which may be ...
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vote
3answers
50 views
Elastic collision with one moving object hitting a stationary object
In an elastic collision, I understand that momentum is conserved and kinetic energy is conserved. If billiard ball of silver (with velocity $v_{(Ag)}$ impacts a stationary billiard ball of aluminum, I ...
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3answers
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Derivative as a fraction in deriving the Lorentz transformation for velocity
Consider a frame $S$ and $S'$ which is coincides at $t=0$ and then $S'$ starts moving with velocity $v$ in $+x$ direction.
By Lorentz transformation equation,
\begin{align}
x'&=\gamma(x-vt) \\
...
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1answer
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If I put an extra marble in a marble-filled-pipe how fast will one drop out on the other side (and is this different from pushing a stick)?
I thought I had found the answer to the question of how fast the other end of a stick will react if I push it (I thought after reading the answers and comments that the other side of the stick reacts ...
1
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1answer
46 views
High velocity particles in the thermosphere
I do not understand why XUV absorption in the thermosphere leads to high velocities.
When I do the calculations on a sheet of paper (momentum and energy) I find that the velocity of (for example) ...
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votes
5answers
196 views
If I pull a long stick one meter towards me, how long will it take before the other end is displaced one meter?
Imagine that I pull a stick one meter towards me. And say the stick is 100 (m) long. My friend looks at the stick on the other side. How long will it take before my friend sees the stick to be one ...
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3answers
50 views
Where does speed and velocity differ? [duplicate]
I'm in Junior High and I still have some confusion towards speed and velocity. They sound like the same thing, where some object moves in a given direction, but there is a difference from both topics.
...
2
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2answers
37 views
Why doesn't $v_T = \omega r$ involve the direction of its variables?
We derived $v_T = \omega r$ by the following procedure, and it's said that $v_T = \omega r$ "is a relation between the magnitudes of the tangential linear velocity and the angular velocity". ...
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2answers
35 views
How much does the resistance force realistically change when driving a car?
When driving a car, one accelerates by having the driving force greater than resistance forces (friction, air resistance, etc). Then, to move at a constant velocity, the accelerator has to be in the ...
3
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2answers
129 views
How to determine net impulse in 2D space?
I am trying to calculate impulse exerted on an individual from a collision in a 2D space using tracking data (working in R on this, I have several thousand observations). I have done a lot already, ...
2
votes
3answers
104 views
If the displacement of an object is not differentiable at some point, say $x(t)=t\sin(1/t)$ at $t=0$, how is its instant $v$ defined? [closed]
If instant velocity at any given time $t_0$ is defined as the derivative of $x(t)$ at $t_0$, what if the derivative does not exist? How are we supposed to deal with $x(t)=|t|$ at $t=0$, or for more ...
1
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1answer
37 views
Acceleration vector at an acute angle to velocity vector
What will be the description of motion of particle if acceleration vector always make an acute angle with velocity vector?
I know that if acceleration vector makes right angle with velocity vector ...
2
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2answers
65 views
Force perpendicular to velocity
In a recent physics class, I was told that force can change the direction of velocity as well as its magnitude simultaneously. My professor drew a diagram in which a particle is moving along a ...
1
vote
2answers
46 views
What will be the minimum drift possible when a boat crosses a river? [closed]
Imagine a boat with a constant speed $v$ that has to cross a river of width $d$. Let the river flow with a constant velocity $u$. I want to know the angle at which the boat should sail in order to ...
0
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0answers
15 views
Angular and Linear Velocity question on Wiki definitions
I have a question regarding the following forms in the case that both angular velocity and radius change in a time quantum. Wiki defines angular velocity in two dimensions as:
$$
\omega = \frac {d \...
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1answer
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Does force perpendicular to velocity change its magnitude?
Of course there is the definition of work as a scalar product of $\vec F$ (force) and $\mathrm{d}\vec r$ (displacement). That would mean that if the force is perpendicular to the velocity of an object,...
0
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1answer
45 views
Proving that acceleration perpendicular to velocity only changes it's direction [duplicate]
In a recent class, I learned about centripetal acceleration and that if a body moves in uniform circular motion the direction of velocity continuously changes implying presence of an acceleration. My ...
13
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8answers
4k views
Velocity is relative, which means acceleration is relative, which further implies that forces are relative as well
So how would we know whether a force truly exists or not. I can be accelerating a car my 5 meters per second squared but another car accelerating with the same acceleration would think that my car is ...
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4answers
65 views
How can we tell if a charge is moving in a Magnetic Field?
In the equation $\vec F=q\vec v×\vec B$ ($\vec B$ is the magnetic field), what is $\vec v$ with respect to?
If we were to imagine $\vec B$ to be infinitely large. How could we tell if the charge is ...
0
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1answer
47 views
Difference in Hamiltonian when using conjugate momenta vs. Velocity
I was recently reading through David Tong's "Application of Quantum Mechanics" (found here) and in it he talks about the completely classical example of a charged particle in a magnetic ...
3
votes
2answers
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Generalization of straight line motion under constant acceleration
My question is that, we all know the three equations of straight line motion under constant acceleration,
\begin{align}
x & =x_{\rm o}+v_{\rm o}\,t+\tfrac12 \mathrm a\,t^2
\tag{1d-a}\label{1d-a}\\
...
1
vote
1answer
45 views
Expressing acceleration in terms of velocity and derivative of velocity with respect to position
we know that
$$a = \dfrac{dv}{dt}$$
dividing numerator and denominator by $dx$, we get $$a=v\dfrac{dv}{dx}$$ provided that $dx$ is not equal to zero or instantaneous velocity not equal to zero
when I ...
0
votes
3answers
47 views
Analysis of motion of a body following an elliptical trajectory
We are all familiar with a body traversing uniformly ( or non uniformly ) along the circumference of a circle. We get nice relations because of the symmetry of the figure and the distance between ...
