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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10
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2answers
108 views

Can one rise through a free-falling rope?

I am a little confused about this question. I cannot imagine that it is possible to rise through a rope (assuming inextensible) that isn't fixed in its upper end. But when I solve this problem, I see ...
1
vote
0answers
20 views

Calculating resultant force along vertical axis when using smartphone accelerometer

I'm making an app which is using accelerometer to automatically detect damages on the route while driving. To estimate if damage occurred or not I'm using accelerometer (acceleration along vertical y ...
0
votes
1answer
34 views

Kinematics of Rectilinear Motion [on hold]

A car leaves an outpost and reaches a speed of $60 m/s$ with a constant acceleration of $3 m/s^2$. It continues at this speed for a time then decelerates at $4.2 m/s^2$. How far will the car be after ...
2
votes
2answers
274 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 ...
-3
votes
0answers
44 views

Movement of a box containig a particle [closed]

A small thought experiment: Imagine a rectangular box in space, containing particle, all resting at $t=0$ from your point of view. At some point in time $t>0$ the particle starts to move with ...
0
votes
1answer
5k views

What factors affect the velocity of an object moving down an inclined plane?

If you have a small toy car rolling down an wooden plank, what factors would increase or decrease the velocity of said car. In the experiment my team originally stated that adding mass to the car ...
1
vote
2answers
452 views

Correct terminology for combined kinematic and dynamic state

The kinematic state is defined as the position and orientation in space. The dynamic state is defined as the associated velocities. What is the correct terminology for the combined kinematic and ...
2
votes
1answer
136 views

How to calculate impulse force of body hitting water?

I'm calculating the force of a body hitting water from a high height. So far I've figured out the velocity at the time of collisions would be 40 m/s. The body is 78 kg. I seem to need the time it ...
4
votes
1answer
196 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
votes
1answer
33 views

Horizontal Velocity of a Projectile thrown from a Cliff [on hold]

If I were to throw a rock of a cliff at 12 m/s as a horizontal velocity, what will the final velocity of the rock become when it hits the ground? I am tempted to say 12 m/s because the horizontal ...
0
votes
0answers
40 views

High School Physics [on hold]

Two girls are standing on a bridge over a river. One girl falls freely and the other ties a rope to her legs. Both jump at the same time from the bridge. The length of the rope is more than the ...
0
votes
0answers
14 views

Kinetic Hysteresis [duplicate]

I have been wondering about this question for quite some time, but, until now, I was not sure how to phrase it without sounding naïve. Let's take Newton's Cradle (just three congruent balls will do). ...
0
votes
2answers
42 views

Initial Velocity Question

What is the initial velocity vertically when a person jumps 0.5 metres into the air, neglecting horizontal movement. Is it just 0 m/s? And the final velocity would be -9.8m/s^2 * the time it took took ...
-1
votes
0answers
13 views

Motion in a Plane Question [on hold]

I don't understand how to do this problem: You are the pilot of a small plane and want to reach an airport, 600km due south, in 4.0h. A wind is blowing at 50km/h[S35oE]. With what heading and ...
-1
votes
0answers
23 views

Vertical Motion Question [on hold]

Question: An object is projected vertically to to the ground in a 20 m/s velocity. After 3 seconds another object is projected from the same position in the same velocity to the same direction. ...
0
votes
0answers
19 views

Analysing kinetic energy in different frames [duplicate]

Case A: Say we observe a body X moving with a velocity of 30 on the +x and we(the observer) are stationary. Case B: The observer moves with a velocity of 50 on the -x. The body X is moving in the ...
-1
votes
0answers
22 views

Pls help me visualise this situation, I'm not able to understand it [on hold]

Find time of flight of projectile thrown horizontally with speed 50m/s from a long inclined plane which makes an angle theta= 45° from horizontal.
-1
votes
0answers
24 views

Projectile motion and bouncing [closed]

Prove that the number of bounces n after throwing an elastic ball on a frictionless surface with a known angle (j)relative to the horizon and the angle of the initial velocity is known also (k)..is ...
-4
votes
1answer
30 views

projectile on an inclined plane [closed]

Is the time of ascent equal to the time of descent? I tried it but I am not being able to prove it mathematically.
1
vote
1answer
39 views

I don't understand the approach used in solving this kinematics problem

The problem text is as follows: During the first half of a straight path, which is at $\alpha_1=60°$ relative to a reference line, a car is travelling at $v_1=72 km/h$. During the second half of the ...
10
votes
4answers
180 views

Problems in the relation $a=v\frac{\mathrm{d}v}{\mathrm{d}x}$

We all know $a = \frac{\mathrm{d}v}{\mathrm{d}t}$. A little application of the chain rule leads to the relation $$a=v\frac{\mathrm{d}v}{\mathrm{d}x}$$ But the above equation shows that $a=0$ whenever $...
-4
votes
1answer
50 views

Differential velocity and acceleration [closed]

A particle moves along the curve $X = 2\sin3t$, $Y = 2\cos 3t$, $Z= 8t$ How to find the velocity and acceleration when $t>0$?
0
votes
3answers
45 views

Why is the sign of the tangential component of acceleration negative in this problem? [closed]

Since the train is slowing down at a constant velocity, shouldn't the acceleration equal zero? Why is it negative in this case?
-1
votes
3answers
728 views

Where does the force to stop a constant velocity object come from?

If a ball hits a wall at a constant velocity, it will slow down and eventually come to rest. Since the ball was at constant velocity, it was not accelerating, and so there was no force. Also, the ...
0
votes
1answer
116 views

Difference between classic velocity and spatial velocity [closed]

I am reading a tutorial about a physics simulator I am using, and it has the following code (in C++, but not important): ...
-4
votes
0answers
24 views

Pls solve this question of projectile motion [closed]

2 particles are projected one by one with same initial velocity from the same point on the ground, they follow same parabolic trajectory and are found to be in same horizontal level, separated by a ...
3
votes
4answers
122 views

Intuitive explanation of the half in the $\frac{1}{2}at^2$ distance equation?

The full equation $$ Xf = X_o + V_o t + \frac{at^2}{2} $$ is integrated from the velocity function (which was integrated from constant acceleration function), right? The problem is, I can't seem to ...
8
votes
1answer
378 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 ...
2
votes
1answer
196 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 greater its acceleration. But in a place where there is no gravity or any other kind of external force, if I apply a ...
1
vote
3answers
514 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? ...
5
votes
3answers
198 views

Does $y$-motion really have nothing to do with $x$-motion?

I am watching a Physics 1 for physical science majors on coursera.com, and in one of the concept tests there is a question that goes like this; "A bullet is fired horizontally from a rifle on the Moon ...
0
votes
3answers
1k views

In a 2D problem with a thrown object, why is the acceleration along the x-axis equal to 0?

I'm starting Physics, and I don't understand why the acceleration along the x-axis is zero for an object thrown near the surface of the Earth. This may be problem specific, but I wouldn't know since I ...
0
votes
1answer
44 views

Equation confusion regarding finding acceleration [closed]

Physics newbie here, sorry if this is super basic... I am learning about kinematic equations and am having difficulty reconciling two of the equations. Let's say I begin driving and after 1 second ...
2
votes
2answers
75 views

Circular Motion. Intuition on vectors as a physics interpretation [closed]

I am a maths undergraduate. I decided to start studying some basic physics trying to be rigorous with the math and uderstand the interpretations of some of the mathematical constructs and see how ...
1
vote
2answers
54 views

If change in position over time is average velocity, why doesn't change in position over time squared equal average acceleration?

For example, let's say a car is experiencing an acceleration of $1$m/s$^2$, for $6$ seconds so it goes $18$m. Now the average velocity is found through dividing $18$m by $6$s which is in line with the ...
0
votes
3answers
542 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 ...
-1
votes
1answer
24 views

How to estimate the relative motion using kinematic equations?

Background I am reading the following thesis: Todosiev, E.P., 1963. The action point model of the driver-vehicle system. On page 9 it describes the relative motion between 2 cars as follows:...
0
votes
1answer
311 views

Kinematics of a differential drive robot

(I am reposting here a question I asked on stack overflow, since it actually sits right in between programming (modeling of 2D physics) and physics proper (kinematics). I think I have the physics part ...
1
vote
2answers
389 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 ...
0
votes
0answers
31 views

Does this calculation give displacement or distance?

So we have velocity as a function of time given $\overrightarrow{v}(t)=(1-2bt)k\overrightarrow{r_0}$ where $b,k$ are positive constants and $\overrightarrow{r_0}$ is a unit vector. It is found that if ...
0
votes
1answer
189 views

Newtons 3rd law, on two opposing discs?

Assume we have a large disc at rest (bottom disc), which is free to move. Above it there is another disc (disc2) that's rotating, and a motor fixed on that large disc (bottom disc) as well, that load ...
0
votes
2answers
205 views

Kinematics equations of motion find x position in 2D from height

I have a question and I thought of 2 possible ways to answer it however the resulting answers are different which means I must be doing something wrong in my calculations. All the below happens 2 ...
7
votes
2answers
2k views

Should acceleration be included in state vector of a Kalman filter?

I'm developing (actually adopting existing solution) a Kalman filter to model motion of a vehicle (UAV or automobile). The state vector will include position, velocity, and, possibly, acceleration. ...
1
vote
2answers
36 views

Is the magnitude and direction of gravity on an object the same as the objects vertical velocity?

I need to make a diagram for an entry level college physics class. I need to show the magnitude and direction of gravity on a flying object and also show the magnitude and direction of the objects ...
3
votes
2answers
380 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 ...
6
votes
1answer
117 views

Why doesn't the relativistic formula for momentum appear consistent with collisions?

The relativistic formula for momentum is $$p = \frac{mv}{\sqrt{1 - \dfrac{v^2}{c^2}}} \,.$$ In the following example, I apply the formula in the most basic way possible to the addition of velocities. ...
0
votes
1answer
62 views

Position / velocity / acceleration vs time graphs when falling towards a black hole

In Newtonian physics, as far as I understand it, for a small object falling towards a massive object, the graphs of position, speed and acceleration vs time look like this: (If the massive object ...
0
votes
1answer
69 views

Projectile motion on an inclined plane [closed]

Two parallel straight lines are inclined to the horizontal at angle $\theta$. A particle is projected from a point midway between them so as to graze one of the lines and strikes the other at a right ...
1
vote
2answers
203 views

Computing Acceleration in mass and pulley system using conservation of energy

I have a question in which a multiple pulley and mass system is being analysed. I can compute accelerations and Tension without any issue using newtons second law. However I am asked to use ...
2
votes
2answers
264 views

Projectile motion - calculate landing angle

A projectile is launched at a $45^\circ$ angle, aiming for a target at a distance of 15 feet away from, and $2$ feet below the starting position. I'm looking for equations to determine: The ...