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.

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3
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2answers
776 views

How can an object move from point A to point B?

If I was at point $A$ and I wanted to walk directly to point $B$, I would have to walk half way to point $B$, but before that I would have to walk half way to halfway to halfway to point $B$ and half ...
0
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2answers
2k views

Homework Question Transformation Energy [closed]

A $1400kg$ car is approaching the hill shown in the figure at $14.0m/s$ when it suddenly runs out of gas. What is the car's speed after coasting down the other side? I think I have to use this ...
-2
votes
0answers
35 views

Please help in this question [on hold]

An object slides down frictionlessly from the top of a fixed straight slope of base 30cm.At least how long does it take for the object to slide down?
0
votes
1answer
70 views

How does angular momentum affect the trajectory of a projectile?

I am thinking about a football thrown in a very tight, very fast spinning spiral. If the football is thrown upwards at a high angle, is it possible for the football to not turn over at the top of its ...
0
votes
1answer
82 views

Magnitude of the average velocity vector (not the average speed)

Thank you ahead of time for taking to look at this. For this following problem we were given an answer however I am almost positive the given answer is wrong. It doesn't even make sense. So here is ...
0
votes
0answers
20 views

Acceleration Vector At highest point of accelerated projectile [on hold]

A projectile is thrown at an angle of $60$ degrees with horizontal with initial speed $20 m/s$,with H being the highest point of its trajectory.Another particle P is now forced to move along the same ...
1
vote
1answer
207 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
2answers
156 views

Ball flying towards me - Newton's third law is violated?

I was trying to answer the question of the flying ball here on the basis of Newtons third law and Momentum conservation. Here is what I have tried. Lets take $m_1$ (the ball) hits $m_2$ (the man). ...
0
votes
1answer
32 views

Maximum Momentum of Neutral Pion

I'm considering the reaction $p + p \rightarrow p + p + \pi^0$. To find the maximum momentum that the $\pi^0$ can have after this reaction in the center-of-mass frame, what I am doing is assuming the ...
0
votes
2answers
464 views

Determine resultant velocity of an elastic particle-particle collision in 3d space

So I have two particles that have collided in 3 dimensional space. I want the particles to rebound off of each other in an elastic manner. How do I determine the resultant velocity vector if I know: ...
3
votes
2answers
238 views

Projectile motion maximum distance to origin

Is there an elegant or easy way to derive the maximum distance from the origin to a point of the parabola created by projectile motion (assume initial position is the origin)? Other than ...
4
votes
4answers
517 views

Is there any such thing as a change in acceleration (ex: 3 m/s/s/s)? [duplicate]

If there exists something like that, then in $distance/time/time/time$, how is it expressed?
4
votes
5answers
287 views

Infinite series of derivatives of position when starting from rest

Suppose you have an object with zero for the value of all the derivatives of position. In order to get the object moving you would need to increase the value of the velocity from zero to some finite ...
-1
votes
0answers
34 views

Calculate the speed of projectile motion [closed]

At $0.5$ of its maximum height, the speed of a projectile is $0.75$ of its initial speed. Calculate the launch angle. Is it possible for me to use calculus to calculate this question?
1
vote
2answers
30 views

Average acceleration versus instantaneous acceleration

Does instantaneous acceleration also changes when direction of velocity changes. I know average acceleration does change.
0
votes
1answer
25 views

Modifying differential equations representing a projectile system to account for an arbitrary force

The following series of differential equations represents a projectile's path when solved (g=9.81): Here is some sample output from this system (with initial values x,y=0, v=1500, theta=1.33): I ...
-2
votes
0answers
17 views

projectiles involving angle of projection [closed]

A projectile is launched with a velocity of 30 m/s. If it just clears a barrier 40 m high at a distance 30 m away from the point of projection, calculate the angle of projection
0
votes
2answers
30 views

How to measure the range of a horizontal projectile?

For an experiment, I'm launching a projectile horizontally to determine the relationship between height and range. Pretty basic stuff. But I'm having trouble coming up with an effective way to measure ...
1
vote
1answer
107 views

Am I right in my understanding of angular motion?

Here is what I've understood about angular motion: If a force is applied at the center of mass of a rigid body, it will undergo pure translational motion. If a force is applied away from the center ...
0
votes
2answers
61 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
vote
1answer
31 views

What is displacement time series?

For a car motion, I have time vector (starting from 0 to 40 with 0.1 increments) so that the time vector is something like $\begin{bmatrix}0&0.1&0.2&0.3&\ldots&40\end{bmatrix}$ and ...
0
votes
2answers
136 views

Animating an Acceleration Vector - Acceleration of object on a crested path in gravitational field

So I was reading in Chapter 3 of my textbook, Sears & Zemanksky's University Physics with Modern Physics by Young and Freedman, 13th Edition, and the discussion took us to a definition of the ...
2
votes
2answers
125 views

At what point does force stop translating an object and start purely rotating it? [duplicate]

At what point (or distance) from the axis of rotation, does force applied on a rigid body stop translating and purely rotating the body? Can such a point even exist? Does the body always have to ...
0
votes
1answer
60 views

Throwing a basketball. What do I need to consider to hit a target? [closed]

This is a question that's been bugging me for some time now and the physics department at school is closed so yeah. Anywho, my question was, given a ball of mass .76, what forces would i have to ...
0
votes
0answers
17 views

Optimal “Blow up” Configuration

Suppose you have three balls glued together. Two are red and one is blue. The system of balls is blown up by an explosion of pure energy (that conserves the center of mass frame) exactly at the ...
0
votes
1answer
27 views

Relativistic Kinematics - 2-Body Particle Decay

Consider the scenario where a particle of mass $M$ decays into two lighter particles of mass $m_1$ and $m_2$. In the center of mass frame (i.e. $\mathbf{p}_1$ and $\mathbf{p}_2$, the momenta of the ...
8
votes
4answers
3k views

Static Friction - Only thing that can accelerate a train?

I'm a computer programmer that never studied physics in school and now it's coming back to bite me a bit in some of the stuff I'm being asked to program. I'm trying to self study some physics and ...
1
vote
3answers
49 views

How do these factors affect the free fall of objects?

Take an example of two balls of different masses being dropped from about 250 meters from the ground. How do the following factors affect free fall: Air resistance. Absence of air resistance. ...
2
votes
3answers
531 views

Does a heavy body move with the slightest force on a frictionless surface?

If I apply horizontal force on a body resting on the ground, my force will be opposed by the frictional force and the body will accelerate at the point where my force exceeds the force of friction = ...
0
votes
0answers
54 views

How does Zeno of Elea's argument on “motion” make sense? [duplicate]

Zeno of Elea (born c. 500 bce) argued so intensely about motion. In one of his arguments he claims – in simple language – "that it is impossible to slap somebody, since the hand first has to travel ...
0
votes
1answer
166 views

Circular motion - is average velocity enough to tell?

If I knew the exact value of constant centripetal force and the average velocity of an object travelling around a circle for time $t$, would that be enough information to determine the final positon ...
1
vote
0answers
42 views

Equivalence of delta functions when calculating decay rate [closed]

$\newcommand{\bs}{\boldsymbol}$ Hello, I'm currently working through the lecture notes of my Theoretical Particle Physics course, and there, we are calculating the decay rate of the following process ...
11
votes
2answers
1k views

Why collide a moving particle with a particle at rest, rather than two moving particles?

I was just reading some lecture notes about relativistic and quantum mechanics, and in the later part of this page the author demonstrates that any relativistic particle collision in the "lab" ...
0
votes
1answer
49 views

In circular motion, what's preventing me from calculating the circumference of the circle, dividing it by time to find the speed of the object?

There are equations to solve for the speed in circular motion. However, is there anything preventing me from calculating the circumference from the given radius, and then divide that over the time to ...
13
votes
2answers
988 views

In an electron-positron annihilation, in what direction are the photons released?

I read that, in an electron-positron annihilation, at least 2 photons are produced, because of the law of conservation of momentum. my question is: in what direction are those photons released? and ...
0
votes
1answer
66 views

Newtons 3rd law, on two opposing discs?

Assume a large disc at rest(bottom disc), and free to move. Above it is another disc(disc2) that's rotating, and a motor fixed on that large disc(bottom disc) as well, that's load is a disc rotating ...
1
vote
0answers
21 views

How to solve Kinematics: two objects meeting in the air

A water balloon is dropped from the top of a 200m high tower. An alert archer at the base of the tower sees the balloon being dropped, waits for 5s, then shoots an arrow at 40m/s straight up towards ...
7
votes
2answers
422 views

what is the kinematics of a particle with complex mass?

particles with real-mass have time-like kinematics ($ds^2 > 0$). particles with zero-mass have light-like kinematics ($ds^2 = 0$). particles with imaginary-mass have space-like kinematics ($ds^2 < ...
0
votes
2answers
26 views

Can Theta be greater than 360 degrees in this equation?

I have a quick question regarding Rotational Motion. I understand the equation x = r (theta) and I know that theta represents the Angular Displacement for a circle but what if the linear distance ...
1
vote
2answers
169 views

Correct terminology for combined kinematic and dynamic state

The kinematic state is defined as the position and orientation in space. The dynamic state is defined as the associated velocities. What is the correct terminology for the combined kinematic and ...
12
votes
3answers
2k views

How does anything move? [duplicate]

So in order for two things $A$ and $B$ to move apart, for example, relative to each other, $B$ can be set into motion away from $A$. This means that we have to increase $B$'s velocity and therefore ...
0
votes
1answer
74 views

Inclined plane, circular motion and the friction

Suppose we have a cylinder on an inclined plane of mass $m$ and radius $R$ moving without sliding (so that $\varepsilon = a/R$). Why is the friction $F$ causing the circular motion sometimes lower ...
1
vote
2answers
60 views

Confusing, can a motor on a moving disc stop the disc?

I've been troubled trying to solve this problem. If a motor is fixed on a moving rotating disc and the motor's rotor has another disc attached to it. What would happen if we attached the motor's ...
1
vote
1answer
684 views

1D Kinematics - Relative Motion involving non-inertial frames of reference

I recently came across a question involving non-inertial frames of reference. I didn't quite understand the way it had been solved due to some conceptual confusion regarding certain deductions made to ...
0
votes
3answers
84 views

Why is the range of a projectile proportional to the square of the initial velocity?

I was watching the MIT lecture about projectile motion and the lecturer asked why $$D=\frac{(v_0)^2\sin(2\alpha)}{g}$$ Why is it $(V_0)^2$ not $V_0$? It is a hypothetical question i know that the ...
0
votes
1answer
28 views

Constrained Motion of Connected Particles, Small Calculation Question

I am looking at this sample problem from Meriam Kraige - Engineering Mechanics Dynamics: When I do the differentiation, I end up with $\large -2\dot y+\frac{x}{\sqrt{x^2+h^2}}$ Where is the $\dot ...
2
votes
4answers
1k views

Is there a formula that gives the position of an object depending on the time, but which doesn't allow the object to surpass the speed of light?

I have found these two formulas: $v = at + v_0$ $x = \frac{1}{2}at^2 + v_0t + x_0$ a is the acceleration v is the velocity x is the position t is the time $v_0$ is the initial velocity $x_0$ is ...
0
votes
1answer
38 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
votes
1answer
54 views

Is this movement possible?

My friend and I were arguing over some random facebook shared video. On this video, one guy throws up a rotating stick then, while it rotates on air, he kicks through it. Is it even possible? Or is it ...
1
vote
0answers
27 views

Projectile Motion [closed]

I've spent some time pondering the answer to this equation, without any success. A cannon is arranged to fire projectiles, with initial speed $v_0$, directly up the face of a hill of elevation angle ...