The description of the movement of bodies by their position, velocity, acceleration (and possibly higher time derivatives, such as, jerk) without concern for the underlying dynamics/forces/causes.
-2
votes
1answer
27 views
Static friction force on a block in a tunnel
Linked to this Comparing Static Frictions
Suppose there is a cuboidal vertical tunnel , and a cubical block in it such that all surface of the block are in contact with the four walls of the ...
0
votes
2answers
66 views
Centripetal Force Acceleration
Suppose you want to perform a uniform circular motion . Then a body performing uniform circular motion horizontally needs an acceleration $= \frac{v^2}{r}$ at each point on the circular path with ...
-1
votes
0answers
29 views
Velocity versus time graph [closed]
A stone is thrown at an angle of $45^0$ above the horizontal x-axis in the +x-direction. If air resistance is ignored, which of the velocity versus time graphs shown above best represents $v_x$ ...
-1
votes
1answer
32 views
Projectile motion: Thrust in x direction = acceleration in x direction? [closed]
I understand that in projectile motion, when an object is solely under the influence of gravity, there is no acceleration in the $x$-direction (with the acceleration due to gravity in the $y$ ...
1
vote
3answers
65 views
Relation between the time, velocity and acceleration
This is question from I.E. Iredov's General Physics:
$1.22$ : The velocity of a particle moving in the positive direction of the $x-axis$ varies as $v = α \sqrt x$, where $α$ is a positive ...
7
votes
1answer
368 views
I reached a result concerning displacement with quantized time intervals. Am I on to something?
A few days ago, I realized a similarity between distance with constant acceleration, $d = v_i t + 1/2 a t^2$, and the sum of integers up to n, $(n^2 + n)/2$. This came up again today when I decided to ...
-4
votes
0answers
35 views
How to calculate average speed when time is greater than distance? [closed]
I understand that average speed is calculated as $\frac{distance}{time}$ however this question says the time is greater than speed. Here's the question:
A bicycle travels 15 Km (kilometers) in 30 ...
13
votes
1answer
193 views
Modelling the movement and jumps of a chalk while drawing a dashed line on a blackboard
You probably know that if you try to draw a line using a piece of chalk on a blackboard , under some conditions (for example, $\alpha<\frac{\pi}{2}$ in the picture below) you will have a dashed ...
6
votes
4answers
120 views
Integrating radial free fall in Newtonian gravity
I thought this would be a simple question, but I'm having trouble figuring it out. Not a homework assignment btw. I am a physics student and am just genuinely interested in physics problems involving ...
1
vote
2answers
130 views
What does it mean if a body has kinetic energy?
What does it mean if a body has kinetic energy?
Does it mean that the momentum vectors of each particle of that body has the same direction?
What about angular momentum?
1
vote
3answers
121 views
How can I solve for time without knowing the vertical velocity?
A guy posted this problem on a forum:
There is a bird sitting on a pole of height h. you throw a rock at it and the moment the rock leaves your hand the bird starts flying horizontally away from ...
0
votes
1answer
78 views
Reachable area of cannonball given fixed initial speed [closed]
The trajectory of a cannonball fired from the origin with initial speed $v_0$ at an angle $\theta$ is given by
$$y = x\tan\theta - \frac{g}{2v_0^2 \cos^2\theta}x^2.$$
For fixed $v_0$, at what angle ...
1
vote
2answers
39 views
Area under a displacement graph
If the area under an acceleration-time graph denotes velocity and the area under a velocity-time graph denotes displacement, what exactly does the area under a displacement-time graph denote?
0
votes
0answers
21 views
Functions of time [duplicate]
Following are the functions of time:
$s(t)$ = distance a particle travels from time $0$ to $t$
$v(t)$ = velocity of a particle at time $t$
$a(t)$ = acceleration of a particle at time $t$.
If we want ...
1
vote
2answers
124 views
Functions of Time
1) Is position a function of time only or also velocity? Likewise, is velocity a function of time only or also the position?
2) The following are functions of time:
$s(t)$ = distance a particle ...
-1
votes
1answer
65 views
Elevator acceleration and velocity equation [closed]
I have a small question about the velocity and the acceleration of elevators.
I am looking for equations which is for a constant velocity and acceleration ( for exemple some elevators didn't have a ...
0
votes
0answers
26 views
Defining collision point in 3D [closed]
I have a problem with finding collision point of two objects with given speed vectors in 3d. Eg:
...
2
votes
1answer
57 views
Rotational velocity of face-on spiral galaxies using spectroscopy
I am doing my first steps in spectroscopy (IFS actually) and how we can learn more about galaxies by using it. I came up with a simple question which, unfortunately, I can not answer:
How can we ...
7
votes
1answer
250 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
1
vote
1answer
103 views
Utilizing maximum acceleration $a$ for displacement $d$ with initial velocity $v_0$ and final velocity $v_1$
Problem
My goal is to move an object from point a to b (displacement $d$) as fast as possible utilizing the maximum available acceleration $a_{max}$, taking into account the initial velocity $v_0$ ...
0
votes
2answers
83 views
Given Angle, Initial Velocity, and Acceleration due to Gravity, plot parabolic trajectory for every “x”?
Given any Angle -> 0-90
Given any Initial Velocity -> 1-100
Given Acceleration due to Gravity -> 9.8
Plot every x,y coordinate (the parabolic trajectory) with cartesian coordinates and screen pixels ...
0
votes
3answers
95 views
Solve for Initial Velocity of a projectile given Angle, Gravity, and Initial and Final positions?
I've found equations http://www.physicsclassroom.com/Class/1DKin/U1L6a.cfm for solving everything (and rearranged to solve everything) to do with projectile motion EXCEPT this, even though it should ...
0
votes
1answer
78 views
Kinematics with non constant acceleration
A particle experiences an acceleration described by
$$
a=kx^{-2}
$$
where x is the displacement from the origin and k is an arbitrary constant.
To what value does the velocity v of the particle ...
15
votes
5answers
273 views
Does the mass point move?
There is a question regarding basic physical understanding. Assume you have a mass point (or just a ball if you like) that is constrained on a line. You know that at $t=0$ its position is $0$, i.e., ...
0
votes
5answers
172 views
Why is momentum conserved (or rather what makes an object carry on moving infinitely)?
I know this is an incredibly simple question, but I am trying to find a very simple explanation to this other than the simple logic that energy is conserved when two items impact and bounce off each ...
0
votes
0answers
34 views
Inelastic relativistic collision [closed]
I have to solve the following problem:
A particle of rest mass, $m_1$, and velocity $v_1$ collides with a stationary particle of mass $m_2$. Find the rest mass $m$ and velocity $v$ of the resultant ...
3
votes
2answers
106 views
Is a heavier skier faster? [duplicate]
Is it true that a heavier skier goes faster? If it is, why is that?
My intuition would be that the speed gained by a skier should be independent from its mass, since both its acceleration and the ...
3
votes
2answers
66 views
Sign of acceleration
I'm developing an application using accelerometer sensor. I'm not good at physics so forgive me if the question is trivial. If I have 3 values of acceleration: $x$, $y$, $z$, I find acceleration ...
4
votes
2answers
1k views
Help me get out of a speeding ticket
I was driving uphill from a complete stop for a distance of .4 miles estimated to take 1 minute in a navigation app. I was pulled over right after cresting the hill. The cop had me on radar going ...
0
votes
3answers
201 views
Deriving equations of motion using integration
Please refer to my school textbook pg48 (of the book, and not the pdf counter) here: http://ncertbooks.prashanthellina.com/class_11.Physics.PhysicsPartI/ch-3.pdf
My doubt is in this context: (right ...
0
votes
0answers
59 views
An unmarked police car passed by a speeding car [closed]
Hi I'm trying to solve the problem
An unmarked police car traveling at a constant speed of 95 km/h is passed by a speeder traveling at 140 km/h. Precisely, 1.00 s after the speeder passes, the ...
0
votes
1answer
45 views
Projectile's angle in midflight
For a missile travelling from (0,0) at angle $\theta$ (to the horizontal) and initial velocity $u$, the y (vertical) position at time t is given by
$s_{y} = u\sin (\theta) t - 0.5gt^{2}$
and the x ...
0
votes
1answer
65 views
Circular motion and centrifugal force
Assuming a race car drives around in a circle of radius r, center (0,0), linear velocity v, and ignoring centrifugal forces and friction I can calculate the position at any time, t.
Angular velocity
...
1
vote
2answers
144 views
Projectile Motion with Drag
The overall goal is to write a Mathematica program that will compute the launch angle that will yield the greatest range with using [RandomInt] function, but I was having trouble with the physics.
In ...
4
votes
2answers
103 views
Best shape to reduce the splash of a droplet?
Our coffee machine catches the last couple of droplets, after your cup is removed on a shape to reduce plash of the coffee droplets.
These shapes are placed inside the spill reservoir.
The shape ...
0
votes
1answer
64 views
Kinematics question [closed]
An electric train accelerates uniformly from rest to a speed of 20m/s which it maintains until the brakes are applied. It is then brought to rest by a uniform retardation equal in magnitude to twice ...
0
votes
2answers
79 views
Do you use the magnitude equation to get speed from an accelerometer?
A guy suggested to me that getting speed from an accelerometer required the use of this equation:
$\text{speed} = \sqrt{x^2 + y^2 + z^2}$
This does not make any sense to me, all that you would get ...
1
vote
2answers
90 views
Doubt in Kinematics
I know that this isn't the place for such basic questions, but I didn't find the answer to this anywhere else. It's pretty simple: some particle moves in straight line under constant acceleration from ...
2
votes
1answer
116 views
Relativistic kinematics of particle decay
Suppose a particle decays to three other particles. The masses of all particles are assumed to be known and we work in the rest frame of the parent particle.
So there are 12 parameters for this ...
2
votes
1answer
138 views
Calculate displacement in position from knowing constant acceleration
I have recently started studying physics at school, and my teacher went over the following equation without explaining about it too much:
$$d~=~vt+\frac{1}{2}a t^2.$$
I have wondered, why would this ...
1
vote
0answers
70 views
What is the initial velocity of a projectile so that it passes through a target point in its trajectory? [closed]
Let's say I have a projectile being thrown by a player in my 2-D game. I want to work backwards and find the initial velocity to apply to the projectile such that it passes through a target point in ...
0
votes
0answers
52 views
Curvilinear abscissa confusion
How's exactly defined the curvilinear abscissa in kinematics? Surfing on the net I found different definitions:
a) Fixed a point $O$ and a direction, the curvilinear abscissa $s$ at a point $P$ is ...
1
vote
0answers
63 views
Getting pairs of angle and velocity for a projectile to a given destination
I'm trying to calculate the initial velocity $v_0$ and angle $\theta$ for a given destination $(x, y)$ with a launch height of $y_0$. Obviously there will be a set of pairs of velocity and angle that ...
0
votes
1answer
156 views
Experiment to measure initial speed of high speed tennis ball?
I want to devise a way to measure the initial speed of a tennis ball fired from a tennis ball cannon, but without using any speed-measuring devices. Just plan distance-measuring and physics formulas.
...
1
vote
1answer
68 views
Shooting a bullet at a system of blocks [closed]
So, I made this question up myself.... and I'm curious about the answer. It requires only secondary-school-level knowledge of physics:
You have a surface (ground) with a certain coefficient of ...
0
votes
0answers
48 views
Driving around a road block? (Quick, turn the wheel !?) [closed]
Consider a car driving with given speed $v$ head-on towards a road block of a certain width.
Car and road block are already so close to each other that a collision would not be avoidable anymore by ...
3
votes
2answers
272 views
Galilean invariance of the Schrodinger equation
I am only asking this question so that I can write an answer myself with the content found here:
http://en.wikipedia.org/wiki/User:Likebox/Schrodinger#Galilean_invariance
and here:
...
1
vote
2answers
110 views
Calculating Average Velocity
I understand that the concept of an average of a data list means finding a certain value 'x', which ensures that the sum of the deviations of the numbers on the left of 'x' and on the right of 'x' ...
0
votes
2answers
115 views
How can I add an acceleration vector to a velocity with a different direction?
I am in my last year of high school and am struggling with some homework. I'm sorry if this question is incredibly stupid, but I simply can't find the answer in my notes.
If I have an object with a ...
0
votes
2answers
141 views
Equation of motion for average acceleration
I am trying to solve the following:
A man of mass 83 kg jumps down to a concrete patio from a window ledge only 0.48 m above the ground. He neglects to bend his knees on landing, so that his ...
