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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725 views

What is the longest distance that can be jumped after swinging from a rope?

In the movie Mission Impossible 3, the main character Ethan Hunt tries to enter a building in Shanghai by swing through the sky, as shown below: The jump consists of 2 sections, the red part, which ...
0
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1answer
381 views

Power, Force Velocity

In any case, if the force and power is constant , does velocity also need to be constant? If no, can you tell me a case. Further can this be extended for non-rigid bodies.
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2answers
626 views

Closest model for relationship between velocity and distance

Which is the model that best shows the relationship between velocity and distance: $v \propto d$ $v \propto d^2$ $v^2 \propto d$ $v^2 \propto d^2$ What I think is from: $$v=at \Rightarrow ...
6
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5answers
12k views

Why there is a 1/2 in kinetic energy formula? [duplicate]

Possible Duplicate: Why is there a $\frac 1 2$ in $\frac 1 2 mv^2$? Hèllo, I have a question about kinetic energy formula. As you know, in kinetic energy formula, we have: ...
0
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3answers
194 views

If my acceleration is -1 ($a=-1\:\rm{m/s^2}$) and I'm standing in the infinite ($x_0=\infty \:\rm m$), could I reach the point $x=0\:\rm m$?

I'm standing in the infinite where $x_0=\infty \:\rm m$. If I have a negative acceleration, could I reach the point $x=0\:\rm m$? Would it be possible to calculate how long would take to reach the ...
2
votes
2answers
990 views

Applying velocity Verlet algorithm

I want to implement a simple particules system using the velocity form of the Verlet algorithm as integrator. Initial conditions at $t=0$ for a given particule $p$: mass: $ m $ position: ...
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3answers
140 views

Estimate quarter mile time

I need to estimate a drag race quarter mile time given the car's weight, bhp and preferably the drive (FWD, RWD, 4WD). I know $v(t) = ds/dt$ and $a(t) = dv/dt = d^2s/dt^2$, but how can I get the ...
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2answers
1k views

Maximum velocity allowed for motion profile with constant jerk

I´m trying to calculate what the maximum allowed velocity for a mechanical axis traveling towards a stop. The maximum velocity must be a secure speed so the axis have is able to stop in time. I have: ...
2
votes
1answer
478 views

Relating angular and linear kinematics

In my physics book "University Physics", there is a chapter on relating linear and angular kinematics. I understand the parts where it shows $v = r\omega$ and $a_{\text{tan}} = r\alpha$. However in ...
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2answers
583 views

Human Kinematics:Does velocity or acceleration become zero at the moment of changing human limbs' direction of movement?

I need to know the answers to following questions about human kinematics. Can anyone kindly help me with it? When human moves hand in one direction then suddenly or not changes direction of hand ...
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1answer
2k views

Trajectory of projectile thrown downhill

I'm teaching myself mechanics, and set out to solve a problem determining the optimum angle to throw a projectile when standing on a hill, for maximum range. My answer seems almost plausible, except ...
2
votes
2answers
576 views

How do I adjust the kinematic equations to avoid reaching speeds faster than light?

I like some 'science' in my 'science fiction', so I started crunching out the kinematic equations for some of the scenarios my characters are getting involved in, and ran smack dab into an issue. ...
2
votes
1answer
536 views

Relative Speed vs speed of light [duplicate]

Possible Duplicate: Travelling faster than the speed of light Someting almost faster than light traveling on something else almost faster than light I've got two questions which are ...
0
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3answers
967 views

The required energy to accelerate a particle from one velocity to another

Say I have a charged molecule running along a linear evacuated tube (so no wind resistance). In the laboratory frame, we can measure that the particle is moving at some speed $v_1$. Provided that ...
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7answers
8k views

I need help with finding distance traveled

How do I find the distance traveled of an object if the speed is not constant?
0
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2answers
137 views

Really basic mechanics and Galilean Relativity question

Consider two solid objects: A and B. System 1: A <----- B 10m/s System 2: A -----> B 10m/s ...
0
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0answers
703 views

Error Analysis, Change in momentum, Kinetic Energy

If momentum of an object is increased by 10%,then its kinetic energy will be increased by? Well, I don't need the solution logically by calculating the change in Kinetic Energy etc, but my question ...
2
votes
1answer
73 views

Sunrise time across the globe?

This question is more astronomy related, I started thinking when I heard from one of my friends living in Jiamusi, that Sun rise at 02:00 and sets at 14:00, I know that this place is more near to ...
1
vote
1answer
164 views

Do observers at different speeds perceive other speeds differently?

I was told that if a plane takes less time to travel from the China to US as opposed to the other direction due to rotation of the earth. I suspect this is incorrect however. From this scenario I ...
0
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2answers
870 views

Time and distance where velocity is a function of time

I'm creating a video game set in space in which spaceships travelling between places accelerate until they hit a maximum velocity. They then travel at that velocity until a time when they need to ...
0
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3answers
2k views

Very basic question: When to use $s=vt$, $s=1/2vt$, $s=at$ and $s=a/t^2$?

Very basic question: When to use $s=vt$, $s=\frac{1}{2}vt$, $s=at$ and $s=\frac{a}{t^2}$? What was the difference between those?
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3answers
788 views

Finding instantaneous speed in MPH given acceleration, RPM and gear ratio

I am still trying to figure out how to (semi) accurately model instantaneous speed after having found acceleration. I have found that at higher RPMs, the resultant acceleration will be lower. I was ...
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2answers
5k views

Finding acceleration for a car after finding torque

I am trying to calculate the acceleration of a vehicle after finding the torque $\tau$. Assuming my Horse Power is 130 and my RPM is 1000, I calculated torque as: $$\tau = \frac{130 \times ...
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2answers
627 views

Motion of a rod struck at one end

Imagine a strong metal rod of uniform density and thickness floating in a weightless environment. Imagine it lies on an X-Y plane, with one end (A) lying at 0,0, and the other end (B) at 0,1. Then it ...
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3answers
871 views

Differential squared vs. differential of squared

Why it is said that $$\frac{dx^2}{dt^2}=\upsilon^2$$ I can only understand the following one: $$\left (\frac{dx}{dt} \right)^2=\upsilon^2$$ Edit: Excerpt from Landau's Mechanics: Execrpt from ...
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2answers
665 views

Given a radius and velocity calculate position of an aircraft banking to make a turn in three dimensional space

Suppose an aircraft is moving at a certain fixed altitude above the ground. It follows a path defined by latitude and longitude. Now if we want to define the position of an aircraft at any point in ...
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1answer
748 views

Relationship between acceleration, velocity and position

I'm learning some applications for equation of motion. But I'm failing to relate velocity, acceleration and position. If $v=\frac{dr}{dt}$ and $a=\frac{dv}{dt}$, why $a$ is $\frac{d^2r}{dt^2}$ ...
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3answers
687 views

A freefalling body problem, only partial distance and time known

Well, I've been trying to figure out a problem which I imposed on myself, so no literal values included. Unfortunately, my brain is not cooperating. The problem states: What is the height from ...
0
votes
1answer
932 views

How do I determine a component of relative velocity?

At a particular instant, a stationary observer on the ground sees a package falling with speed v1 at an angle to the vertical. To a pilot flying horizontally at constant speed relative to the ...
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2answers
1k views

Kinematics - concept question

A child tosses a ball directly upward. Its total time in the air is T. Its maximum height is H. What is its height after it has been in the air a time T/4? Neglect air resistance. Ok so I know that ...
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1answer
73 views

Does the movement of things in the universe will cease one day?

To start or change the movement, we need a force. This force, according to Newton's second law, is variation of quantity of motion from the object per unit of time.Therefore, if the variation does not ...
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votes
5answers
10k views

Why does work equal force times distance?

My 'government-issued' book literally says: Energy is the capacity to do work and work is the product of net force and the 1-dimensional distance it made a body travel while constantly affecting ...
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2answers
4k views

What is displacement? Position relative to a reference point or change of position

What is the "official" or most useful definition of displacement in the context of kinematics? There are two common ones: Displacement is the length and direction of a line from a fixed reference ...
0
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1answer
253 views

Looking for a way to simplify a physics formula [closed]

I have the following physics formula: $$d = \frac{1}{2} at^2$$ where d is equal to half (at) squared where: d is distance a is acceleration t is time I need to simplify this to get the ...
0
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2answers
506 views

Find vector position in time give this graph?

Graph is position x position. There are 3 points, $A$, $B$ and $C$. $A(0,2)$ $B(4,2)$ $C(6,0)$ Particle travels from $A$ to $B$ and from $B$ to $C$ at constant $v = 2 ~m/s$. Find vector ...
3
votes
1answer
4k views

How do kinetic energy and linear momentum relate?

It took me quite a long time to click my gears in place and even then I'm not sure it's completely correct. The problem is that I need to understand these concepts (physics concepts; not just these ...
0
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1answer
101 views

A Satellite's Perspective

If a planet is spinning east to west and there is a satellite spinning from west to east... Can the satellite travel at a speed sufficient to make the planet appear, from the vantage point of the ...
3
votes
1answer
233 views

A practical deceleration question

My friend is a U.S. Army paratrooper. Today, through an unfortunate series of events, he was jerked out of a C-17 traveling at 160 knots by his reserve parachute. First-hand accounts describe it as he ...
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1answer
3k views

Question on Projectile Motion equation [closed]

A golf ball is shot into the air from the ground. If the initial horizontal velocity is 20m/s and the initial vertical velocity is 30m/s, what is the horizontal distance the ball will travel ...
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2answers
309 views

Confusion regarding geodesic of thrown ball - curved or Cartesian coordinates?

I'm confused trying to understand what's happening in terms of spacetime geodesics when a ball is thrown and its trajectory plotted, height against time to give a parabola. I read (from more than ...
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2answers
235 views

Trains travelling at different speeds towards a station C

Here's the question: Consider two stations A and B located 100 kilometer apart. There is a station C, located between A and B. Now trains from station A and B start moving towards station C at ...
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votes
4answers
971 views

A person weighing 100 N stands on some bathroom scales in a lift. If the scales show a reading of 110 N, which way is he going [closed]

Can someone answer and explain it please. Here are the options: Moving downwards and decelerating. Moving downwards with a constant velocity. Moving upwards and decelerating. Moving upwards with a ...
2
votes
2answers
737 views

What is the displacement of an accelerated and relativistic object?

Displacement in an accelerated classical object is: $$s=ut+\frac {at^2}{2}$$ What is the displacement of an accelerated relativistic object? In Newtonian mechanics there are two types of ...
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2answers
2k views

Would this model of a boat move according to Newtons 3rd Law?

If i have a small toy boat with a sail, and i attach a fan onto it, FACING THE SAIL, which runs by solar. Once the fan turns on will the boat move or will it remain at rest. Apparently it wont because ...
3
votes
3answers
6k views

Maximum range of a projectile launched from elevation “dumbed down”

I am trying to conceptually understand why the angle which produces the greatest range for a projectile launched with an elevation is not 45 degrees. I have exausted all other options, and I hope that ...
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1answer
2k views

Simple Projectile Motion Question

A volcano erupts 50m below the sea level. A rock leaves the crater at 20 m/s at an angle 30 deg with the vertical line. The rock has a mass of 15kg. IGNORE WATER RESISTANCE. It gets out of the water, ...
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1answer
2k views

What's wrong with this equation for harmonic oscillation?

The question: A particle moving along the x axis in simple harmonic motion starts from its equilibrium position, the origin, at t = 0 and moves to the right. The amplitude of its motion is ...
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2answers
982 views

Does acceleration at an angle to velocity change the direction?

During an interval of time, a tennis ball is moved so that the angle between the velocity and the acceleration of the ball is kept at a constant 120º. Which statement is true about the tennis ball ...
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2answers
286 views

Kinematics Problem

The question asks me to find the angular velocity. Now I do not want you to solve my homework, I want explanation please. It states that the acceleration of point P is $\vec{a}= -3.02 \vec{i} ...
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2answers
2k views

Sign of Velocity for a Falling Object

I'm working on a homework problem in Mathematica. We have to graph the height and the velocity of a function given an initial height and initial velocity. However, when I do the graph for the velocity ...