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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79 views

Acceleration during collision with ground

For my physics class, I have to calculate an objects acceleration while it came to a stop. It was traveling at $6.26\: \mathrm{\frac{m}{s}}$ at impact, and travels a distance of $0.025\: \mathrm{m}$ ...
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2answers
43 views

Simple velocity and kinematics!

in this question, how to i solve for the velocity of object at point W? What my thinking was is that you know x to w is 25, therefore 25m/25s = 1s so 1s/2 = 0.5s, so: v = d/t = 25/0.5 this is ...
3
votes
3answers
305 views

A particle of mass $m$ moves with constant speed $v$ along the curve $y^{2}=4a(a-x)$ [closed]

I have complications to do the following problem: A particle of mass $m$ moves with constant speed $v$ along the curve $y^{2}=4a(a-x)$. Find its velocity and acceleration vectors. My first idea was ...
6
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5answers
8k views

If an object moved 5 meters in a second, how can its velocity be 10 m/s?

I am reading the tutorial on physics classroom.com, and am at Meaning of Slope for a v-t graph. It gives data for an object experiencing an acceleration: This is the corresponding chart for the ...
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1answer
495 views

Determining $y$ coordinate of charged particle motion [closed]

I've tried several different ways, with a tutor, and with other colleagues. One of my colleagues has even gone to the professor with whom he worked out an equation for the component, and it was later ...
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1answer
592 views

Help understanding a potential energy problem [closed]

Apologies if the following problem does not seem to involve potential energy, it is a homework problem that is labeled under the potential energy chapter. Question While a roofer is working on a ...
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3answers
149 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 ...
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2answers
3k views

How to plot $(x,y)$ coordinate of projectile motion (with air-resistance)? [closed]

I am trying to plot a graph to show the difference in projectile motion when it has air-resistance and when it doesn't have air-resistance. I set the mass, $v_0$ and $\theta$ as constant I can plot ...
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1answer
89 views

rectlinear motion with constant acceleration [closed]

Friends, this is a numerical homework problem. I tried my best to solve it but my answer is not matching with the one given at the back of the text book. Please help me out: A motor car moving at a ...
2
votes
2answers
216 views

Time variation of the distance between two falling objects [closed]

I have solved this question below from my textbook. My answer differs from the one given in the book. I have tried my best to see where I am wrong. I need your help to find the truth of this question. ...
2
votes
1answer
151 views

Velocity of hitting the ground when falling forward

A friend of mine fell while he was snowboarding which led to a discussion. He mentioned that, in general, if your center of mass is traveling at a certain velocity, and you fall forward, your head ...
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1answer
106 views

Displacement inside the moving Object

Suppose say a person is standing over the moving bike and he jumps while bike is moving, bike will move forward & person will land in same point at which he jumped, relative to earth position ...
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7answers
37k views

What does the magnitude of the acceleration mean?

I am a little confused as to what the magnitude of acceleration is and what it means.
2
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3answers
738 views

The velocity formula $\mathbf{v} = \mathbf{u} + \mathbf{a}t$ for 1D, 2D, 3D . What is the difference?

Could I use $\mathbf{v} = \mathbf{u} + \mathbf{a}t$ for calculating velocity in these 3 different dimensions? If not, what's the difference between these 3 dimensions? How would you calculate ...
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2answers
145 views

Blueshift and increase in energy!

Imagine that there is a car and it is not moving but its headlights are on. There is a wall in front of the car but is very far away. Right now energy is being used only in switching on the ...
1
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0answers
86 views

Force needed to change momentum, from fixed position

I have a situation where I want to change the velocity of a mass, by applying a force from a fixed position. For example in the diagram below, the mass starts with the initial velocity in the upper ...
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1answer
52 views

Why does angle deviation of a satellite not captured my Mars decreases as the Velocity of the satellite increases?

When a satellite is not captured by a planet, it is moving sufficiently fast. so why is it that the angle deviation of the satellite decreases as its initial velocity increases?
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0answers
1k views

Find initial velocity when given max height of 100m [closed]

A ball is thrown straight up. The height of the ball above the ground in (m) is given by the function: $$h(t)=-5t^2 + vt + c$$ What is the initial velocity if you want the ball to reach a max height ...
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0answers
17 views

Reference request for motion & related topics [duplicate]

I'm starting a Robotics course at grad school and I could use some help to relearn and revise my concepts in the following topics : Kinematics Rigid Body Dynamics Rotational Motion and Linear ...
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2answers
195 views

Finding the height of a power-line

Question: To find the height of an overhead power line, you throw a ball straight upward. The ball passes the line on the way up after 0.80sec , and passes it again on the way down 1.5sec after it was ...
8
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2answers
1k views

Non-Constant Acceleration due to Gravity

Recently, I had the first physics lab for my university physics course. This lab was fairly simple, as we were merely using a computer and a distance sensor to graph the position, velocity, and ...
0
votes
2answers
55 views

A Kinematics Problem [closed]

Problem: From the top of a building of height h = 100 m I throw a stone up with velocity 10 m/s. What is the maximum height it reaches, and when does this occur? First I solved for $h_{max}$, ...
1
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1answer
377 views

elevator goes up [closed]

An elevator goes up 180 m by first accelerating at a constant rate of 1.0 m/s2, then staying at a constant speed of 9 m/s and then decelerating at a constant rate of -­‐‑1.0 m/s2. How much time does ...
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1answer
93 views

Motion of rigid body system in absense of work

In the absence of work on the system, is there a closed form equation for the motion of a set of constrained rigid bodies (let's say, using Revolute (ie: simple pivot) constraints)? If the bodies are ...
0
votes
1answer
149 views

Why do these equations result an incorrect unit for acceleration?

Hello everyone. Imagine an object moving around a certain point on a circular orbit. Magnitude of the velocity is constant during the motion ($|v|$). The orbit radius is $r$. (I'd better notice ...
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0answers
59 views

Motion of objects (beginner) [closed]

I have begun physics and we are seeing systems of reference as an introduction.Now I have a small exercise which I'm not sure of, I would need you to check if it's correct or not. There are two ...
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1answer
4k views

Calculating angle of projectile motion [closed]

I realize that similar questions have been asked but I'd like to put my problem here and what I have to make sure everything is right. So my problem is: I've got a rock $2.5$ meters above the ground ...
0
votes
2answers
183 views

Difference between the two equations for acceleration

I came upon this while studying S.H.M. Well,is there a difference between writing $$a=\frac{dv}{dt}\;$$ and $$a=v\frac{dv}{dx}\;$$ do they differ on the basis of one being a vector and the other ...
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votes
1answer
231 views

Parametric equations in ballistics

while studying some material on ballistic trajectories (the basic gravity-only parabola), I've tried to come up with closed-form expressions for another case, where in addition to gravity we add a ...
0
votes
1answer
141 views

Homework: A parachutist jumps from a plane [closed]

I need help with the following problem. I think I almost have it . . . A parachutist bails out and freely falls a distance of $y_1$. Then the parachute opens and thereafter, the parachutist ...
1
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3answers
1k views

Direction of motion

What does the term direction of motion actually mean? Is it a direction where a particle is moving or the direction of its velocity? For example, what is the direction of motion of a projectile in ...
2
votes
0answers
74 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 ...
2
votes
1answer
540 views

Mandelstam variable equality derivation for $s$-channel process

I am supposed to show that the Mandelstam variable $s=(p_1^2 + p_2^2) = 4(P_{cm}^2 + m^2)$ for an electron/positron interaction, where $p_1$ is the incident 4-momentum of the electron and $p_2$ is ...
7
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2answers
143 views

Why does a small object stay in one place after being shot from a big gun?

This video shows what I mean. Basically they shoot a bullet from a huge gun at an iPhone. What I don't get is why does the phone move only so little after being shot? As far as I can tell it isn't ...
3
votes
2answers
249 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 ...
0
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1answer
1k views

Distinguish between instantaneous speed and instantaneous velocity

I encountered a line in my text book of physics that: Average speed over a finite interval of time is greater or equal to the magnitude of the average velocity. But instantaneous speed at an ...
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2answers
69 views

how to find last position given a time

I found this formula (I dont know its name) and I'm trying to apply it in order to find the last position given a time and velocity. $ s = s_0 + v_0 \cdot t + \frac{1}{2} \cdot a \cdot t² $ given $ ...
2
votes
2answers
831 views

Mass Effect on Slingshot Motion?

For my physics class (I'm a high school student), we created slingshots. Our task is to predict the distance a projectile, launched from a slingshot using surgical tubing, would land. We aren't given ...
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2answers
955 views

Finding the optimal angle of a projectile motion [closed]

I am trying to solve a task in which I need to calculate the optimal angle($\alpha$) with which the projectile will land the furthest from a height ($h$), so what I basically have is the equations for ...
1
vote
1answer
385 views

Applying multiple forces to one object and calculate net movement and rotation?

I'm working on a small game as a hobby project, and I've run into a problem that would seem simple, to me, but that I can't find any information on or solution to. How would one go about figuring ...
3
votes
2answers
771 views

Oscillation of a rolling sphere in a bowl [closed]

This is a homework task. I already came to a result but I am very unsure. The task: In a bowl with the shape of a semi-circle ($R$ = 0.5m) a sphere (there is no specification for the size of the ...
1
vote
1answer
123 views

Exertion from swinging on a playground swing

I've read about how by tilting one's body one changes one's center of mass while swinging on a playground swing, and thereby increases the energy of the swing. But I would like to get a better sense ...
1
vote
2answers
291 views

Need clearing up on vector decomposition in motion physics

I've been pursuing physics on my own, and I need something cleared up. Say I have two arbitrary objects, I have their velocities, I know when the collide, I have their normal vectors, etc. I know ...
1
vote
1answer
259 views

Equations of motion of particle mass on parabolic surface

Given a parabolic surface $$ Z = \frac{\Omega^2}{2g}\left(X^2 + Y^2\right)$$ My textbook (Introduction to Geophysical Fluid Dynamics, 2nd ed, p.50) states: "Provided that the paraboloid is ...
0
votes
1answer
86 views

What is empirical mean of centripetal acceleration

We have this formula for centripetal acceleration - $a = v \frac{d\theta}{dt} = v\omega = \frac{v^2}{r}$ but in case of usual acceleration i know that speed in $t_1 = v_0 + a \cdot (t_1 - t_0)$ but ...
0
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1answer
67 views

Second law of thermodynamics and motion

The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems spontaneously evolve toward thermodynamic equilibrium—the state of ...
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0answers
48 views

prediction of a moving object

OK, this may be a hard question to answer and really all I am looking for is an equation as I don't even know what to call this. This is all for a game so bare with me please. In the game two ...
2
votes
4answers
4k views

Force applied to wheel in pure rolling motion at contact point with road

Suppose a wheel with radius $R$ is resting on a non-inclined surface. A torque $\tau$ is applied to the wheel center. In an attempt to prevent wheel from spinning, the ground applies a static friction ...
1
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2answers
626 views

Increase in velocity by loss of mass? [closed]

A trolley of mass 300kg carrying a sand bag of 25kg is moving uniformly with speed of 27km/h on a frictionless track. After a while, sand starts leaking out of a hole on the floor of the trolley at ...
2
votes
3answers
177 views

Why isn't centripetal acceleration considered in this problem

Fairgoers ride a Ferris wheel with a radius of 6.00 m. The wheel completes one revolution every 30.0 s. If a rider accidentally drops a stuffed animal at the top of the wheel, where does it land ...