All Questions
Tagged with motion or kinematics
4,321 questions
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What is the locus of the velocity vectors of a boat navigating in the sea under the presence of some force?
I am a mathematician and know nothing about physics, although I am trying to solve a problem related to physics. If someone could help or provide some suggestions, I would be grateful.
I have a speedy ...
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1
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What is the equation if that projection starts SHM on the $x$-axis from extreme position?
Consider A particle performing Uniform Circular Motion.
We know that its projection on diameter performs SHM.
Then, if that projection starts SHM on the y axis from mean position, then $y=A\text{sin}(...
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1
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In $a = dv/dt$, is $a$ the net acceleration? [closed]
While going through the calculus approach to accelerate, we have,
$$a = dv/dt, $$
I think, here, v and a should be in the same axis,
is my process correct?
in a planar motion in two dimensions, it ...
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2
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2
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95
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Where do exerted forces come from?
I think my confusion stems from this: if a book is resting on a table I understand that the force of gravity acts on the book and as it is in equilibrium, the table exerts a force equal in magnitude ...
-1
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1
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Derivation of the function for the position of a particle given that a constant force acts on the particle which always points to fixed point [closed]
A particle of mass $m$ is moving with initial velocity v. A constant force F acts on the particle in a direction which always points to a fixed point P. If initially the direction of v was ...
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20
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Simulating two-body decays in the specific direction
How to simulate the 2-body decay of some particle with mass $m$ moving with the given 4-momentum $p^{\mu}$ into two particles 1,2 with masses $m_{1}, m_{2}$ such that, say, the particle 1 will have ...
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How to explain the phenomenon of air bag, when have one object hit air bag and one object catapult from air bag
Problem of this phenomenon is in title.To describe this, I separate it into 3 phases;
M1 hit airbag, 2) Air moving inside air bag caused by pressure gradient ,
3)M2 flew away caused by air moving to ...
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3
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Where does the negative sign disappear?
The defining equation for simple harmonic motion is such
$$a=-ω^2x$$
When we find the centripetal acceleration of an object in orbit we use the formula
$$a=ω^2r$$
As a consequence of the accleration ...
1
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2
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142
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Average velocity showing different results
I was solving a question, in which, a particle has travelled a distance $s$, with initial velocity $0$ and constant acceleration.
So the equation of motion becomes,
$$ v = a t \tag{1} $$
and
$$ v = \...
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1
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Why is the 2nd approach is incorrect? [closed]
Question: A particle is thrown upwards from the ground. It experiences a constant air resistance which can produce a retardation of $2 \, \text{m/s}^2$ opposite to the direction of velocity of the ...
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2
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2
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659
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A ball was thrown horizontally but it has zero horizontal initial velocity? [closed]
A question I faced reads
"A ball is thrown horizontally from a height of 25m and hits the ground with a speed that is 4 times its initial speed. What is the initial speed?".
It said the ...
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39
votes
4
answers
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When a bus goes around a corner, does the person sitting at the back travel further distance than the person sitting at the front?
This is a bit of childish question.
When a bus goes around a corner, does the person sitting at the back travel further distance than the person sitting at the front?
My thought is no because the bus ...
- 501
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2
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50
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How a tire send a car flying? [closed]
https://abc7news.com/118-freeway-crash-caught-on-video-los-angeles/13027476/
The incident happened on Thursday, March 23, in Chatsworth, Los Angeles. In which a vehicle went flying into the air after ...
1
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1
answer
41
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Determining star position and velocity to deduce closest approach?
I am trying to replicate the results found for Gliese 710's closest approach of ~0.05 parsecs in 1.3 million years approximately. I thought that by plotting the sun at (0,0) and using the stars ra,dec,...
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4
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77
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Percentage change in K.E for a given change in momentum
I couldn't get through this 'easy question' that was in my morning exam, it goes
Q. If linear momentum of body is increased by 50%, then K.E of that body increases by....%
**My solution **
K.E = $E=\...
- 387
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259
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Are there only 2 types of motion -- Translational & Rotational?
When searching up the different types of motion, results show circular motion, translational motion, oscillatory motion, rotational motion, periodic motion, etc. But just to clear things up in my head,...
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4
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261
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Why isn't the tangential velocity of circular motion zero?
Why is tangential velocity 2πr/T if the body's total displacement in the end of one revolution is zero?
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3
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93
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Why catching a ball of high trajectory easier in Cricket match? [closed]
my question is related with Projectile motion, it describes about the high velocity of ball on its trajectory. it asks about the conditions of height, time of flight, range as well.
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1
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123
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Is it possible that a ball is thrown downward/upward with zero initial velocity? [closed]
The way I've seen the motion of a ball thrown vertically:
All balls are thrown with an initial speed. In my understanding, it's not possible that something goes either upward or downward with nonzero ...
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2
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1
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83
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How to correctly integrate when acceleration is time dependent?
The problem is as follows:
A ball moving in a straight line is experiencing acceleration $a(t)=kt$ until it arrives at a certain length $l$ when some time $t_f$ has passed. The initial speed and ...
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2
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142
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Kinematics: Given the velocity as a function of the position, is it possible to derive the velocity as a function of time?
If a particle is subject to a constant acceleration $a$, the position of the particle after a certain time is given by the formula $s(t)=\frac{1}{2}at^2$. This immediately results in the formula $v(t)=...
-1
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1
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49
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Finding radial acceleration from $xy$ vector cordinate [closed]
I know that is a silly question but i cant figure it out.
Suppose we have
$$ \textbf{R} = A i + B j $$
and want to find the radial acceleration.
We know that the radial acceleration is
$$ \ddot{r} -...
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0
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80
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Could Spider Man Have Saved Gwen Stacy given the "spring constant" of spider silk?
I was looking at some stuff online about Spider Man in the famous scene from the comics where he accidentally breaks Gwen Stacy's neck, because as he shoots his web down to stop her falling from the ...
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3
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181
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Is a body in uniform circular motion in equilibrium?
I know this question has been asked a myriad different times, but nowhere can I seem to find a definitive, final resolution to it.
Is a body in uniform circular motion in equilibrium?
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2
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127
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Why does a mass winding up around a cylinder not lose it's velocity? [closed]
All solutions online I could find to this question takes it as a preconceived fact that as the mass winds, its motion will be perpendicular to the acceleration provided by the thread and hence the ...
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1
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129
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Absolute Angular Velocity - How to use?
From my dynamics course, we were introduced to the so-called absolute angular velocity of a rigid body. Below is a short diagram:
The following equation for the velocity of point P on a rigid body is ...
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1
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0
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79
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Velocity of Non-relativistic Electron [closed]
I am working on the course MIT Quantum Physics I, Spring 2016. I am stuck in the following problem:
Question: In a classical universe, we might try to build a hydrogen atom by placing an electron in a ...
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3
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98
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Question regarding aparent position and velocity of an object
A time lag is always involved while observing objects. Due to this reason we can never observe the correct position of an object at a particular time. We will see it where it was some times ago. Is ...
user380105
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69
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Avg. velocity in plane polar coordinates
It's fairly easy to describe velocity, acceleration and displacement in plane polar coordinate system is the time interval is approaching to 0, but how can we calculate velocity, acceleration and ...
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2
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2
answers
108
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A contradictory thought process of a simple problem
Lets say there are 2 point particles A and B separated by a distance $x_{0}$ whose velocities are $v_{1}$ and $v_{2}$ along the positive X-axis respectively such that $v_{1}>v_{2}$
We can clearly ...
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2
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2
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172
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Constraint Equation and Equation of Motion
I was doing a question which was to find the number of generalized coordinates needed to describe a particle with the motion:
$x(t)=2a\sin(\omega t) $
$y(t)=a\cos(2\omega t)$
So I solved it and found ...
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1
answer
106
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What really is oscillatory motion in physics? [duplicate]
Is it that oscillatory motion must be to-and-fro motion about a mean/stable equilibrium position, or it does not qualify as true oscillatory motion? Or, is it that most of the oscillatory motion has a ...
0
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2
answers
67
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Kinematics - Solving Projectile motion equation not giving all possible solutions [closed]
The following problem is given (from PHYSICS For Scientists and Engineers with Modern Physics - text book):
"A home run is hit in such a way that the baseball just clears a wall 21 m high, ...
4
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1
answer
145
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Determining a direction/projection/heading for an object in 3D space after it has been rotated
I hope this is a good place to find an answer. Regardless, Worldbuilding looks like a great forum to follow.
I'm not a math wiz and I've tried to tackle this problem many times over the past decade or ...
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2
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Paradoxical result arising regarding velocity
I was working on a problem that goes like this
Bob beats Judy by 10 m in a 100-m dash. Bob, claiming to give Judy an
equal chance, agrees to race her again but to start from 10 m behind the
starting ...
- 279
2
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1
answer
63
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Right notation for SI units/dimension in polynomial function?
I integrated a jerk-function three times (acceleration, velocity, position) to get the resulting function $s(t)$ for the position. I am not sure how to use the SI units or dimension in the function.
...
new_bee
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3
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169
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Why does the equation of a wave contain the term $\omega t$ instead of $vt$ in the wave equation $y=A\sin (kx-\omega t)$?
Why does the equation of a wave contain the term $\omega t$ instead of $vt$ in the wave equation
$$y=A\sin (kx-\omega t).$$
I think of the constant $k$ which for higher values increases the frequency $...
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2
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1
answer
65
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Intercepting a moving target with limited change in velocity
I have an already moving object A trying to intercept a moving target B in 3D space, and I have limited acceleration (for example not necessarily enough fuel for the optimal acceleration).
A is ...
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1
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228
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What does instantaneous velocity mean? [duplicate]
What does instantaneous velocity mean?
on google it says "Instantaneous means something happens very quickly, in a single moment. It's similar to the meaning of "instant", but most ...
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1
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61
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The distance problem [closed]
Say a car has to move from Point A to Point B on the surface of the earth. The car starts from rest at Point A at time $t=0s$ reaches point B at time $t=10s$ with a constant velocity of $1000 m/s$. ...
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Wave vector components from 2 column data
if I have 10 data in each column for speed (2D), how to connect those data as wave form?
I need to find the components of wave vector ($k_x, K_y$).
I request any suggestions regarding this.
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6
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Does a squared unit require squaring the value?
I would like to know if an acceleration number would remain squared in
$$ v=v_{o}+at $$
Such as 1.35 m/s^2, for example, would end as
$$ v=v_{o}+(1.35^2)t $$
or simply as
$$ v=v_{o}+(1.35)t $$
Thank ...
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1
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99
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Given a distance, and velocity as a function of time, how do I find the time taken to travel the distance? [closed]
Given the velocity of a particle as a function of time V(t), and a distance between two points on a straight line (from point A to point B), I would like to find the time it will take the particle to ...
- 605
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0
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A ball dropped onto a rotating wheel of various frequencies experiment issues
I'm doing a experiment to find the relationship between the frequency of the rotating wheel and the horizontal distance travelled by the ball dropped onto it. I am manipulating the frequency of the ...
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0
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41
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How to measure Angular Velocity observed from A non-stationary frame?
A stationary observer observes a rotating disc with radius 1 at angular velocy w. Let's say this disc is centered at origin in xy plane (all angular Velocity mentioned in this question is around the ...
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4
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100
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Understanding velocity as a vector quantity [closed]
Why is velocity classified as a vector quantity. Can it be explained by the same way as force referring to the Phys.SE post Where am I confused about force addition?
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192
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How do kinematic equations work regardless of mass of the object?
I came across this question (very simple):
"A dog is running and starts to get faster at $2 ms^{-2}$ for $3s$. If the dog covers $20 m$ over this time, what velocity did it start with?"
...
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2
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137
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Polar coordinates: Orthonormal basis
In polar coordinates we have $r= c(\hat{r})$, where $c$ is the distance of a point from origin, and $r$ is the position vector.
So, what is the use of $\hat{\theta}$ especially given that it is always ...
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1
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50
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Time dependence of de Broglie wavelength of an electron with initial velocity $V\hat{\imath}$ and in a uniform magnetic field $B\hat{\jmath}$
I am supposed to comment on the time dependence of de Broglie wavelength of an electron with initial velocity $V\hat{\imath}$ and in a uniform magnetic field $B\hat{\jmath}$.
Obviously since the ...
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3
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96
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Why is it wrong to find centripetal acceleration using change of velocity over change of time?
This question asks to find the centripetal acceleration by giving the initial and final velocity over the change of time.
As shown, my book combined two rules to find the acceleration. I utterly ...
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