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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11 views

Finding $x$ and $y$ component of a dog running [on hold]

I'm new to physics and cant get through this problem atm... A dog running in an open field has components of velocity vx = 3.5 m/s and vy = -1.4 m/s at time t1 = 10.3 s . For the time interval from ...
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1answer
34 views

If two cars have the same acceleration at time $t$, are the velocities of the cars the same at time $t$?

So when I look at the question logically, I reason that if I had two cars: Range Rover and BMW, at time t, I could pump the gas and make them accelerate at the same rate at 0.5 m/s^2 but I could be ...
-1
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0answers
62 views

What does $dx/dt$ mean in this formula? [on hold]

The formula i'm struggling with is A1a in the appendix of this paper (A double pendulum model of tennis strokes. Rod Cross, University of Sydney. 2006) - LINK. I understand all the other terms of the ...
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2answers
370 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 Newton's third law and momentum conservation. Here is what I have tried. Lets take a ball mass of $m_1$ (index 1 is the ...
3
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2answers
87 views

Watching Airplanes Fly Toward You

Recently, I was enjoying the stars on a cool summer night and saw an airplane flying toward me from the distance. I observed its path as it started out as a small dot in the distance until it flew ...
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0answers
67 views

Question about speed riddle and relativity [on hold]

My father posed to me the following riddle. suppose there was a 2 mile stretch and you wanted to average 60mph. You went the first mile at 30 mph assuming instentanious acceleration how fast do you ...
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1answer
34 views

Finding Velocity from Acceleration

I have an Acceleration signal (from accelerometer) for a bat that hits a ball. Is it possible to obtain the Velocity of the bat and the ball with just the acceleration signal? My intuition obviously ...
3
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1answer
185 views

General motion of a cone on an inclined surface

Suppose that a solid cone is placed horizontally on an inclined surface and is initially at rest. How will the cone move when it starts motion due to its weight? I know that its motion depends on the ...
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0answers
32 views

Moves without acceleration [on hold]

The distance between boat A and boat B is a. Two boats move with no accelaretion with speed =v from two direction. Boat A moves in direction of the line which is perpendicular to the lakeshore while ...
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0answers
36 views

Rain man problems [on hold]

In order to protect himself from the rain, a person is standing holding an umbrella at right angle to the horizontal surface. The rain is falling at $10\ \mathrm{m/s}$ when the velocity of the wind is ...
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0answers
18 views

Two particles of different velocities travel through a region of time-dependant acceleration. At what time do they meet afterwards? [on hold]

Two projectiles: $P_{1}$ and $P_{2}$ have velocities $v_{1}$ and $v_{2}$, both propagting in the x direction and starting at $x=0$. They propagate with constant velocity over a distance $L$ and reach ...
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2answers
47 views

Calculating acceleration via differentiation of velocity [on hold]

I am just starting with calculus and kinematics. I saw this particular question: The velocity of a particle at a distance $x$ is given by $v^2 = 4\cdot (x \sin (x) + \cos (x))$. Find the ...
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0answers
18 views

kinematic constraint of spacecraft

I am now reading a paper about trying to use convex optimization to solve the attitude control of spacecraft. However, I do not have background on the physical part: Let 1. $\omega(t) = ...
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0answers
24 views

MY QUESTIONS TOPIC IS KINEMATICS [on hold]

A model rocket fired from the ground ascends with constant upward acceleration. After 1.0 s from firing a small bolt is dropped from the rocket and after 5.0 s from firing, its fuel is then finished. ...
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2answers
235 views

How to find Tangential/Radial/Angular Velocity for motion in any curve?

Is the radial velocity responsible only for changing distance between objects and the component perpendicular to it only for change in direction? If so why? Please try to give a different explanation ...
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1answer
29 views

Calculating relative velocity in three dimensional space

Given two points $\mathcal{A}$ and $\mathcal{B}$ in $\mathbb{R^3}$ whose position and velocity vectors are, respectively: $$\mathbf{r_A}=\begin{pmatrix}r_{A_{x}}\\r_{A_{y}}\\r_{A_{z}}\end{pmatrix}$$ ...
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0answers
16 views

the motion of a body in a resisting medium [on hold]

the motion of a body falling from rest in resisting medium is described by the equation dv/dt = (a - bv); where a and b are constants. the velocity at any time 't' is? PS: please explain it fully
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2answers
41 views

Is distance considered only for objects which have already moved?

I have this confusion concerning distance and speed. Typically, we express displacement and distance relative to a reference point, which we regard to be an unmoving location. As displacement has a ...
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2answers
75 views

Use equations to create a realistic problem [closed]

Given the following equations: $100$ m = $0$ m + ($50 \cos\theta$ m/s)$t_1$ $0$ m = $0$ m + ($50 \sin\theta$ m/s)$t_1$ - $\frac{1}{2}(9.80$ m/s2$) t_1^2$ I am supposed to make up/create a real-life ...
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0answers
52 views

Calculating distance travelled with non-constant acceleration [on hold]

A car is accelerating from $ v_0 = 0 $ to a velocity v in a straight line. The acceleration is given by $a = a_0 - kv^2 $ where $ a_0 $ is constant. Calculate the distance s travelled when the ...
-1
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5answers
72 views

How can I find initial and final velocity? [closed]

Is there a way to find initial and final velocity if I only know the acceleration and distance and which formula must I use? I do not know the time either. EDIT Thank you for all your answers! You ...
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3answers
7k views

Finding the max height of a ball launched as a projectile using work-energy

A ball is launched as a projectile with initial speed $v$ at an angle $\theta$ above the horizontal. Using conservation of energy, find the maximum height $h_\text{max}$ of the ball's flight. Express ...
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2answers
51 views

Finding acceleration due to gravity of a 2D projectile

Can I find acceleration due to gravity of a 2D projectile given only the peak of the projectile, the point of impact, initial angle, and initial velocity? Specifically what is missing is the initial ...
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2answers
65 views

Average acceleration: why I am getting different results?

Let's consider a simple school problem. A car starts moving during 3 seconds with a constant acceleration of 1 m/s^2. Then it stops accelerating and moves 3 seconds more with a constant speed. Find ...
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0answers
29 views

Relative velocity question [closed]

How can I decide where to move the man.... left or right in the questions of relative velocity? A standing man on a horizontal road observes rain falling with velocity 20 m/s at an angle of 30 ...
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1answer
43 views

Time traveled assuming instant acceleration/decelaration

I am working on sort of a motion planning algorithm where I need to estimate the time it takes to travel along a certain path of points (straight lines between consecutive points, i.e I am assuming ...
8
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1answer
369 views

Is it possible to determine particles' velocities from their crossings on a ring?

2 particles are constrained to move in a ring. Both particles begin moving at $t=0$ from $p=0$, each particle moving in the opposite direction of the other. It is known that they are moving at ...
3
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2answers
54 views

Best way of calculating average acceleration in lab experiments

I am doing a lab experiment that works as follows. An object moves along the $x$ axis with an initial acceleration and then moves with a pretty constant velocity that may slightly vary within $20\%$ ...
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1answer
48 views

Would displacement vs time of circular motion be a sin/cos curve or parabola

If you were to graph the displacement from one specific point in a circle of an object rotating, example the boomerangs displacement from the thrower. Would you use a parabola, since in a cos/sin ...
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0answers
36 views

When this CD is spun so fast that it shatters, why does the warped shape move slower than the surface?

In this video where a CD is spun abnormally fast to the point of shattering, one notices from the writing on the CD that the surface is spinning faster than the warp "shape" is. In other words, the ...
1
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1answer
39 views

Intuitive picture for Mandelstam $t$

In tree-level electron-positron scattering one has two possible channels corresponding to Mandelstam variables $s$ and $t$. The $s$-channel ist fine, there $\sqrt s$ is just the center of mass energy ...
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1answer
125 views

In perfect vacuum (no external force), if I apply a small amount of force to a body, will it continue to accelerate forever?

According to the equation F = ma, the greater the force applied to a body, the more is it's acceleration. But in a place where there is no gravity or any other kind of external force, If I apply a ...
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0answers
31 views

Homework, Kinematics [closed]

Please look at the picture. I really don't know how to solve it. The graph is complex. Can anyone explain the solution in details? The answer is 12. Thanks a lot!
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0answers
18 views

How to find the new position of the car-like robot using Ackermann equations! [closed]

I know the current position of the car-like robot. The linear and angular velocities for the car-like robot is also known for each time step. So what are the equations for deriving the new position ...
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0answers
13 views

Theshold energy in a collision [closed]

Should be simple one but I can't get it work through, the question is as follows: Consider an endothermic reaction where an incident particle $a$ collides with a rest target particle $A$. Given the ...
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0answers
19 views

Particle interaction kinematics in lab frame

Attempting a question from a past paper on scattering kinematics, fixed particle mass $m$ is struck by another particle mass $m$ with kinetic energy $T$. By evaluating $s$, $t$ and $u$, and their sum ...
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2answers
70 views

Doubt on series springs [closed]

Here is a description of the motion of two springs in series. The premise is that the force on the two springs is the same. This is derived from the following reasoning: when I pull the mass with a ...
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0answers
13 views

Calculating distance using gforce and time [closed]

The $g$ force on a freely falling body is always $1g$. We can find distance by using $S = \frac12gt^2$. 1) What about if the body is in horizontal motion? 2) How can we find the distance based on ...
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2answers
86 views

I don't understand the formula of constant deceleration required to prevent a vehicle collision

As I was looking for the formula that an Intelligent Speed Assist technology use to calculate the required deceleration that a vehicle must apply avoid collision, I found this one: $$a = \frac{V^2_0 ...
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3answers
1k views

Speed of an object in air versus in vacuum

Okay, imagine that you are shooting a rocket down a tunnel that is 60 miles long and the rocket is travelling at 60mph, so the rocket should reach the end of the tunnel in a hour, right? Yep, in an ...
0
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1answer
126 views

Find constant acceleration needed to reach point (possibly related to projectile motion on slopes) [closed]

Given a particle with a position $p_0$ and an initial velocity $\vec{v_0}$, what acceleration $\vec{a}$ do we need to reach point $p_1$ and how long until we have reached $p_1$? The magnitude of the ...
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1answer
60 views

Why does everything written on a page appear in concentric circles when we rotate that page? [closed]

When i put a pencil in the middle of a paper and rotate it very fast, whatsoever is written on it, will appear in concentric circles. What is the reason behind this phenomenon and what is it called?
8
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5answers
16k 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 ...
4
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3answers
199 views

Is $\dfrac{dx}{dt}$ a fraction or not?

I am new to calculus and during my mathematics class my sir defined $\dfrac{dx}{dt}$ as $$dx/dt=\lim_{t\to t_1}\dfrac{f(t)-f(t_1)}{t-t_1}$$ and my sir made a clear statement that $\dfrac{dx}{dt}$ ...
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1answer
176 views

Explanation about friction force directions of two moving bodies in contact

can someone explain me why in this scenario (picture below) we have a friction force Ftr12 in the same direction as movement (left part of the picture, case 1 ) and how these directions of friction ...
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1answer
46 views

Vector Derivative: General Case

From "An Introduction to Mechanics" by Kleppner & Kolenkow, SIE-2007, Chapter 1 (Vectors and Kinematics), Section 1.8 - "More about the derivative of a vector". In this section, towards the ...
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3answers
8k views

Does an object's kinetic energy increase, decrease, or stay constant when it reaches terminal velocity while falling?

Does an object's kinetic energy increase, decrease, or stay constant when it reaches terminal velocity while falling?
6
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2answers
1k views

What is the highest energy position for a double pendulum? And for which energy positions is it chaotic?

Math/physics teachers love to break out the double pendulum as an example of chaotic motion that is very sensitive to initial conditions. I have some questions about specific properties: For a ...
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1answer
21 views

Does object traversing in linear motion have a constant bearing rate?

If an observer is moving at a constant rate and constant direction and another object traverses in front of the observer and is also moving in a fixed direction at a constant rate, will the bearing ...
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0answers
12 views

Kinetic gas theory: How large are rotational and vibrational energy for a linear diatomic molecule?

Let's say one has given a temperature of a simple linear diatomic gas like Hydrogen $H_2$. From the temperature one knows the energy of the gas, but how does this energy "split up" to the different ...