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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3answers
27 views

How can I calculate how high an arrow goes when all I know is its initial speed?

I'm not familiar with English physics terms so bear with me. If I shot an arrow straight up and it went off with a speed of 21 m/s, how high up would it go? (air resistance is insignificant). My ...
0
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0answers
29 views

Why does a curved spacetime result in a movement?

If gravity is not a force but a curvature of spacetime, where does the motion towards the center of gravity come from? To put it differently, why would two objects in a space fall towards each other ...
0
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1answer
15 views

If an object launches off of a table at a given velocity, calculate angle below the horizontal when it hits the ground?

So this is a basic kinematics question that I'm having trouble understanding. Here is the question verbatim: A hockey puck slides off the edge of a table with an initial velocity of 28.0 m/s and ...
0
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1answer
11 views

Ball launcher angle calculation based on distance [on hold]

I am trying to calculate the angle of a ball shooter (powered by two spinning wheels) based on my distance (as calculated with an ultrasonic sensor) to the base of a goal that is mounted 5.5 feet ...
2
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8answers
459 views

Why is there a universal speed limit?

I am looking for an answer that does not rely on Special or General Relativity -and without recourse to the fact that the speed of light is frame invariant. Is there another way of showing this ...
0
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3answers
229 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 ...
0
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1answer
29 views

Calculating stopping distance of a car on a slope

I'm having trouble setting up a homework problem properly. We are given the following: A given car can brake to a stop from a speed of 60.0 mi/h in a distance of 123 ft on a level roadway. What ...
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0answers
28 views

Motion question [on hold]

I have been struggling to understand how to do this question so some guidance would be great. A racing car of mass 941kg accelerates from 28km/h to 102km/h over a distance of 297m. Frictional forces ...
2
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1answer
523 views

Tangential and radial acceleration in projectile motion

I'm currently learing kinematics, specifically projectile motion and as an example in my textbook is a bullet fired at some angle. I understand the derivation of formulas to describe that motion and ...
0
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2answers
357 views

Horizontal and vertical acceleration of a ball on a slope?

I understand that you resolve the components of the balls weight parallel and perpendicular to the slope in order to calculate the force due to gravity that actually acts down the slope. The ...
0
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0answers
27 views

How do I find the co-ordinates and speed of this particle on the x-y plane? [on hold]

I got this question from an old physics exam paper. I'm trying to use the kinematics equations to solve this question but the x and y co-ordinates keep confusing me. Here's the question: A particle ...
3
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1answer
169 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 ...
1
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2answers
398 views

Projectile, air resistance and wind

So for my school project I am working on a projectile simulator and air resistance. So I have looked at this. Equations for an object moving linearly but with air resistance taken into account? ...
2
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1answer
33 views

A couple of questions regarding work to velocity exchange [on hold]

I was tasked to express the velocity of the cube of mass $m$ at point B using the constants given in the picture below. Friction could be ignored, and the cube could be presumed to reach B with the ...
7
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1answer
344 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 ...
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0answers
29 views

Problem - Escalator [closed]

I need help in resolving the following problem: On a recent weekend, Anna was rushing through a shopping centre doing her shopping she had occasion to use the escalator 3 times. The first time the ...
0
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1answer
20 views

a question on work and kinetic energy [closed]

A bullet has a mass of 0.02kg and is moving with a speed of 10m/s. It can penetrate 10cm of a given target before coming to rest. If the same target is only 6cm thick, what will be the speed and ...
0
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1answer
199 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
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1answer
340 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 ...
1
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1answer
41 views

Difference between classic velocity and spatial velocity

I am reading a tutorial about a physics simulator I am using, and it has the following code (in C++, but not important): ...
1
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0answers
34 views

3 Particle problem with a difference

Please read this completely, it is not the typical question you expect. 3 particles are at the corners of an equilateral triangle with side a. Assume that particle 1 is at (0,0), particle 2 is at ...
4
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2answers
58 views

Free body diagram with forces of friction

I'm reallizing that I'm very confused on how to make a free body diagram of forces in some situations where there is friction between two objects. I'll make an example where I cannot figure out what's ...
0
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0answers
32 views

Finding the distance a spaceship would travel given a time of departure and velocity

Let's say a spaceship leaves Earth at a day t and with velocity v. Is there a way to know how many kilometers it will cover to arrive on Mars? This would be a trivial question were it not by the fact ...
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1answer
56 views

Relative velocity of a boat traveling on a river [closed]

I am confused about relative velocity. So suppose a boat is traveling upstream on a river and a crate is dropped overboard. The boat continues to travel upstream for 60 minutes and reaches a ...
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0answers
25 views

Could someone please provide what each of these motions mean and provide a formula to it? [closed]

Each time I try to organise each of the motions separately, I get somehow somewhere confused along the way and keep on getting stuck. The following motions: Average distance Average displacement ...
0
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1answer
32 views

Use of the chain rule in kinematics problems for quantities given in function of the position [closed]

I don't understand the use and the meaning of the application of the chain rule in some situations. For istance, consider a 2D motion and the equation of trajectory described by a point $y=f(x)$. ...
1
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1answer
19 views

How fast does a long object bent at the center need to be travelling in order to boomerang?

At an angle, of course. Standard pressure, average temperature, and calm wind. Bonus question: Can an object that is not bent boomerang at all? If yes, how different would the equations for this ...
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1answer
75 views

What's the formula for the speed of an accelerating car?

I am trying to find a formula that closely describes the speed of an accelerating car over time. I have found many graphs on the internet, but so far no formulae to generate them. For my purposes I ...
-1
votes
1answer
37 views

a problem on circular motion [closed]

Question:A cyclist is riding with a speed of $7.5$ m/s. As he approaches a circular turn on the road of radius $80m$, he applies brakes and reduces his speed at the constant rate of $0.50$ m/s every ...
1
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1answer
64 views

Does this count as a proper derivation of the formula for work and kinetic energy? [closed]

$v_{av}$ = average velocity, $d$= distance, $a$ = acceleration, $m$ = mass Given: $$v_{av}*t=d$$ $$t=\frac{v_f-v_i}{a}$$ $$v_{av}=\frac{v_f+v_i}{2}$$ Then: $$\frac{v_f+v_i}{2}*\frac{v_f-v_i}{a}=d$$ ...
0
votes
2answers
45 views

How to interpret the equation of motion of a point that changes its acceleration

I'm trying to understand more deeply the equations of motion for a constantly accelerated 1D motion. Consider a point that moves with constant acceleration $a$ and that, at a certain moment $\tau$ ...
0
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1answer
47 views

Relationship $v_A^2-v_B^2=2a_t\Delta s $ for motion with constant tangential acceleration [closed]

I can not understand a relationship in the general motion in the plane. I am considering a point, which follows a curved trajectory. Indicate A and B two different position of the trajectory and $v_A$ ...
1
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4answers
58 views

Introductory physics: first second of free fall

While doing my physics homework I encountered an acceleration problem that I've been unable to solve. Here, is the data table of the objects motion. At 1 second, why does the "Dist-meters" slot of the ...
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1answer
45 views

Finding angle between two displacements [closed]

Consider two displacements, one of magnitude 6 m and another of magnitude 8 m. What angle between the directions of this two displacements give a resultant displacement of magnitude (a) 14 m, (b) 2 m, ...
0
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1answer
123 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 ...
0
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0answers
71 views

Equation of motion of a free particle

We know that the equation of motion of particle can be derived from the respective action. But in the book I am reading, the author is saying: ... timelike worldline of a massive particle is ...
0
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0answers
11 views

Calculating the distance of a piston from the crank center

I stumbled upon this [https://en.wikipedia.org/wiki/Piston_motion_equations#/media/File:Piston_motion_geometry.png ] and was wondering, if you can determine the position of the piston (x) by the law ...
1
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0answers
27 views

How to find tangential and normal unit vector to a trajectory from the equation?

Considering a 2D motion in a plane and the equation of the trajectory of a point $y=f(x)$, I don't understand how exactly $\frac{\mathrm{d}y}{\mathrm{d}x}$ can be used. In particular if I'm looking ...
1
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2answers
52 views

accelerating and non accelerating duality of matter

Kinetic energy of any object , assumes accelerating nature of the object as it is derived from equations of motion for uniformly accelerated objects and the work-energy theorem which deals with ...
0
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1answer
324 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 ...
1
vote
0answers
45 views

What happens if an aeroplane travels in a pilot mode in a straight line with no stop? [closed]

Ex. If a plane flew upwards straight it would reach outer space but what happens if it travels below the horizon in a straight line. Will it be traveling around the earth? How? And what about it if it ...
0
votes
3answers
136 views

How to account for inertia in kinematics?

Alright, I'm only in AP Physics and I asked my teacher and he couldn't help me... I'm making a 2D physics engine and I'm having problems when it comes to gravity between objects and I think its ...
0
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0answers
14 views

Relations between unit vectors in polar and curvilinear coordinates

I'm a bit confused about the relations between unit vectors in curvilinear and polar coordinates in a plane. Let $u_{R}$ be the radial unit vector in polar coordinates and $u_{N}$ the normal unit ...
1
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0answers
12 views

Calculation max speed for a particular speed profile, distance and time?

For work I have to calculate the maximum speed for a machine. The machine has a certain speed profile which must be followed. Besides this this speedprofile has to be followed within a certain time ...
0
votes
2answers
114 views

Find the force needed to accelerate body to a certain velocity for a certain time with respect to drag force

So, the problem is straightworward when we suggest that air resistance force is constant: $$ \vec F = \frac {\vec V_1 - \vec V_0} {t} m / b $$ $$ \vec V_0, \vec V_1 - \text {initial and final ...
107
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17answers
29k views

Why does kinetic energy increase quadratically, not linearly, with speed?

As Wikipedia says: [...] the kinetic energy of a non-rotating object of mass $m$ traveling at a speed $v$ is $mv^2/2$. Why does this not increase linearly with speed? Why does it take so much ...
1
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0answers
25 views

Is there a way to find the optimal angle to launch an object to get maximum distance when there is an initial height? (Projectile motion) [duplicate]

I know that the optimal angle to launch an object at ground level is 45 degrees; however, i want to know that if there is anyway to get the optimal angle to launch an object to get the maximum ...
0
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2answers
31 views

(+)/(-) Acceleration & (+)(-) Velocity

Does a negative acceleration mean an object is slowing down? Does a negative velocity basically mean you are moving at an opposite direction? The sign is just direction?
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0answers
12 views

Height estimate by step profile?

With so many current apps in mobiles tracking number of steps based on analyzing the accelerometer's measurements in time during a walk, I was wondering the following: Would it be possible to ...
4
votes
1answer
27 views

Transformations and kinetic energy

From the equation $E_k=\frac12mv^2$ you can determine more energy is necessary to accelerate a mass the higher your initial velocity is. For example, three times more energy is necessary to accelerate ...