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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Calculate distance with variable acceleration [duplicate]

I know the time and I know the force that acts horizontally on a particle. The problem is that the force is F=k(D-V), where k and D are constants. So at the beginning where the particle has zero ...
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0answers
28 views

Elastic Plastic with Kinematic Hardening Material Model

I have a model which calculates the rate of deformation tensor using the Green-Lagrange strain rate, the material velocity gradient and the gradient of deformation tensor. $$\bar{\bar{D}} = ...
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2answers
34 views

In terms of forces and kinematics, why does a projectile, thrown forwards, bounce forwards?

I'm curious to know why a tennis ball bounces forwards after it has made contact with the ground considering I throw it forwards and downwards at the ground. I understand that is bounces up because ...
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4answers
212 views

Why the round trip instead collision time?

From Newton's second law, the $\Delta t$ is defined as the collision time, but why in this case, it can be assumed to be the value of time between successive collisions on 1 wall? If I have an ...
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2answers
96 views

What happens when two bodies collide in a dynamics point of view?

I'm a high school student learning about energy and momentum. What confuses me is the things with elastic and inelastic collisions. I completely (in my opinion) understand those concepts in energy ...
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1answer
73 views

Conservation of mechanical energy isn't giving me the right answer? [closed]

I have been trying to solve this question: You are working for a shipping company. Your job is to stand at the bottom of an 8.0 m long ramp that is inclined at 37 degrees above the horizontal. You ...
2
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1answer
64 views

finding velocity along a curve with kinematic equations using time

(i'm "not" looking for coding help. i need help setting up the math.) i'm writing a program for a physics class to find the velocity of an object across a random curve. where the only force acting on ...
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3answers
230 views

How to prove the average velocity formula without calculus

I often see the formula: $$ \overline v = \frac {v + v_0}{2} $$ in physics textbooks, to describe the average velocity for an object moving with constant acceleration. This formula is often ...
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1answer
43 views

Why trajectories approach to origin tangent to the slower direction?

I am reading non-linear dynamics from Strogartz. Suppose, I have two solutions of a non linear system: $x(t) = x_0e^{at}$ and $y(t) = y_0e^{-t}$, where $a\in \mathbb{R}$. Now it is clear that,for ...
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2answers
97 views

Elastic collision between two circles [duplicate]

I am trying to calculate the final velocities of two equal mass 2-dimensional circles after an elastic collision. I have tried to figure it out using formulas I know from high school physics, but ...
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2answers
44 views

A drop falling in the condensed air

A drop is falling in humid air with air resistance equal $F_r = - \alpha v^2$. In $t = 0$ the drop is ideally spherical, $h$ above the ground, has mass $m_0$ and velocity $v_0 = 0$. What mass and ...
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1answer
39 views

Find the height and the velocity of the object [closed]

A bolt is detached from the lower part of an elevator cabin that is ascending with velocity 6meters/second and for 3 seconds comes to the point from where the elevator started to ascend. Find: in ...
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1answer
21 views

Coefficient of restitution belongs to kinetics and not to kinematics?Reason

The Coefficient of restitution is defined as $$e=\frac{v_2-v_1}{u_1-u_2}$$ $$v_2\to \text{final velocity body 2}$$ $$v_1\to \text{final vel of body 1}$$ $$u_1\to\text{initial vel of body 1}$$ ...
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2answers
47 views

Rocket altitude [duplicate]

I have a model rocket I'm planning to launch. I heard from someone that you can calculate the altitude by timing the rocket from the time it takes off to the time it lands. Does anyone know how to do ...
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3answers
121 views

Can a particle have no instantaneous velocity at all points of the path taken but a finite average velocity?

I have a question on kinematics. Say the path traced by a particle is given by a Koch curve or Koch snowflake. Now consider the particle starts from some arbitrary point $A$ on the curve and ...
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1answer
79 views

A fast object (0.8c) getting overtaken by another fast object (0.9c): why don't times agree?

I'm trying to work on an exercise in Wolfgang Rindler's book "Introduction to Special Relativity" and I'm stuck on the following exercise: Two particles move along the x-axis of S at velocities ...
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2answers
44 views

Finding time when acceleration is not constant

First of all, I'm sorry if this is an ignorant question, but it is for a personal project and its been bothering me. Let's say you want to accelerate in you car for some amount of time, then let off ...
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1answer
73 views

Special Relativity Kinematics Problem with My Wrong Solution [closed]

You are traveling toward a large fixed mirror at a constant relative speed 0.20 c0 . At t = 0, when the mirror is a distance d from you, you emit a light pulse from a lantern and then detect the ...
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2answers
57 views

Experimentally measuring a sphere's moment of inertia

I'm a freshman in Physics and I'd like to design an experiment to measure a sphere's moment of inertia except, well, I'm not very familiar with the concept beyond the formulas it comes with as it was ...
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2answers
42 views

Does really a spring compresses placed between two blocks when one block is given force on a frictionless surface?

When Spring is placed between two bodies on a frictionless surface it gets compressed when one block is given kinetic energy as told by my physics teacher. But it should not compress as there's no ...
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1answer
37 views

Formula - Bounce height with respect to time

I'm trying to graph a bounce with respect to time. I have these formulas: $\frac 12 mV_2^2 = mgH_2$ and $H_2 = \frac{1}{2} \frac{V_2^2}{g}$ I will have a series of $H(t)$ formulas as I know how to ...
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0answers
17 views

Modelling Rotational Motion using Linear Accelerometer [closed]

I am using a 3 axis linear accelerometer on the wheel of a car at position $R/2$ (Where $R$ is the radius). Now i am modelling the equation which i will be getting at the output of the accelerometer. ...
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2answers
38 views

How can I calculate the change in velocity? [closed]

"A runner runs at 4 m/s on a circular track constantly. A and B are opposite points on the track, so A is the starting point and B is halfway around the track. Calculate his change in velocity from A ...
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1answer
53 views

Why can the ball travel at the same speed to the left like the toy car and at the same time travel vertically upwards? [closed]

Imagine a toy car travelling at constant speed to the left. Balls are projected vertically upward one at a time, at 1-second intervals. Edited question : Why is the ball travelling at the same ...
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30 views

Particle Disintegration Range of Angles (Landau& Lifshitz)

In the particle disintegration problem in the book by Landau and Lifshitz (pg 44 question 3), it is asked to find the range for $\theta=\theta_1+\theta_2$, where $\theta_1$ and $\theta_2$ are the ...
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11 views

Kinematic equations of a cascading particle decay

This paper discusses different measurable quantities that can be used to search for unknown particles at particle accelartors. For the following decay it introduces the invariant mass $m_{XY}$: It ...
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2answers
99 views

How much energy is needed to move an object in lossless environment?

How much energy is needed to move a 1 kg object for a distance of 1 meter horizontally in a constant speed (assuming no energy is wasted)? Does it matter what is the movement speed (assuming not ...
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1answer
135 views

Understanding rotational motion on a rough surface

I am having trouble gaining an intuitive understanding of rotational motion for an object rolling on rough surface, and I have a few questions regarding it. Let's say that there's a cylinder that ...
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0answers
36 views

How does the ball move? [closed]

A lift is moving up with a constant velocity. The passenger in the lift throws a balls horizontally with constant velocity. How will the ball appear to move for a person standing outside the elevator. ...
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5answers
164 views

Pushing down on the gas pedal of a car a good example of jerk?

I'm trying to think of the clearest examples to demonstrate the concept of jerk to a layman. Ignoring drag and making other reasonable assumptions (friction is conveniently there to only allow you to ...
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1answer
30 views

Trying to find out how to calculate how fast something moves from the force [closed]

In our introductory physics class (8th grade) I/we would like to find out how fast a piece of paper needs to be moving to break a chopstick. [Similar to putting a straw through a potato] We will be ...
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2answers
60 views

Obtaining Velocity from Acceleration

I'm following a research paper (PDF via RG), part of which is about using the accelerometer of a smartphone to assist the user's positioning via WLAN. Accelerometer is used to determine if the user ...
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0answers
55 views

Circular Motion: Rubber Stopper Lab

During a lab I was doing involving uniform circular motion, we had to spin a rubber stopper horizontally via a rope. At the bottom of the rope, there was some weights. I have to answer this question ...
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1answer
44 views

Deriving some uniform circular motion equations

My question basically boils down to this. How do we derive these relationships. 1.)What is the relationship between radius and centripetal force? (inverse, but why?) 2.)What is the relationship ...
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2answers
102 views

Calculus versus Algebraic Kinematic Equations

Deriving the first equation of motion using either algebra or calculus you get the exact same thing, but my knowledge was that you use integral calculus in physics when you have a varying variable, ...
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3answers
61 views

Initial speed in homework problem [closed]

This is a homework question. I tried to solve it, but failed. I had to translate this question, so please forgive me if it is poorly worded. In this question you can ignore the atmospheric ...
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1answer
63 views

Vectors and Scalars [closed]

How is Momentum $mv$ integrate form a Vector product to produce a Scalar [ Kinetic Energy $(1/2)mv^2$]? Is this mathematical proof of the vector to scalar change in Absolute Calculus, Number Theory, ...
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1answer
37 views

Calculating offset when crossing a river with speed profile [closed]

I am having some issues putting the theory I learned into practise. We have an exercise, that goes as following: A swimmer wants to cross a river with width b. The swimmer heads straight to the other ...
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2answers
47 views

Why is it that when I do some substitution, I get $p=1$ for a photon? [closed]

I know that this is wrong, but where did i make a mistake? I just use a few equations and substitutions and I get that the momentum of a photon is one. Here is my math: $p=h/λ$ $p=hf/c$ (substituted ...
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2answers
80 views

The acceleration of the centre of mass [closed]

Given two balls that are thrown straight up in the air at a speed of $40 \:\mathrm{m/s}$, $0.10 \:\mathrm{s}$ apart. One ball is twice the mass of the other. The heavier ball is thrown second. ...
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votes
1answer
30 views

What is the Kinetic energy of two objects as viewed from their center of mass [closed]

A body of mass $m$ moving with velocity $v$ is approaching the second object of same mass but at rest. The kinetic energy of two object as viewed from their center of mass is: (a)$mv^2$(b)$\frac 12 ...
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0answers
18 views

estimate the launch point and expect the place falling of a shell in the air

suppose that we have a shell in the air, and detected by a particular radar, how do I estimate the launch point and expect a place falling and time will takes to reach its target? I want help please! ...
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1answer
41 views

How do you interpret definite-integrating of both sides of an equation?

Consider a particle is moving at an acceleration of $a=f(s)$ [$s$ stands for particle's location) if we have the initial velocity of a particle then what is the final velocity? So... we know that ...
-1
votes
1answer
57 views

2D Kinematics and Projectile Motion [closed]

In this page, I have finished most of the problems. Some of them I am unable to figure out. For 3 a-j, is it possible to solve this problem given parts a and b, that is, can I solve these problems ...
0
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1answer
70 views

Trajectory of a projectile in a three dimensional space [closed]

$g$: the gravitational acceleration—usually taken to be $9.81\:\mathrm{m/s^2}$ near the Earth's surface $θ$: the angle at which the projectile is launched $v$: the speed at which the projectile is ...
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0answers
24 views

Calculate the parabollic trajectory

In order to calculate the parabollic trajectory (or ballistic) I need intrinsic equation. Now I need to integrate this equation but I don't know how. I would appreciate so much if you help me!
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1answer
34 views

Kinematics equations: wrong place value [closed]

A marble is launched horizontally off a 93.0 cm high table causing the marble to land on the floor 1.85 m from the base of the table. a.) How long was the ball in the air? b.) With what velocity must ...
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4answers
136 views

How do I use the kinetic energy formula using mass as lbs and velocity as mph?

I understand that the formula for kinetic energy is: $(1/2)mv^2$, which is equal to 1 Joule or 1 N-m. If I want $m$ to be my weight (say 150lbs) and $v$ to be 40mph how do I apply it to this formula? ...
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4answers
172 views

Motion caused by Internal force

I would like to clarify whether an internal force in a system can cause it a motion externally? My Physics teacher and also other tuitions in my area tell that only external forces can cause motion of ...
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0answers
43 views

The angle of a rifle to hit a target (How to make approximations to find numerical answers) [closed]

The specific question is this: A target appears at a distance of 1250m with the centre of the target 1.2m above ground level. If the sniper was firing from the prone position, the tip of the ...