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.
0
votes
4answers
60 views
When we take time derivative of a function of time, then is the result another function of time, again?
(I'll try to explain my question by one known example), for example where the velocity is a function of time v(t) then its time derivative (which is acceleration: $a=\frac {dv}{dt}$) is another ...
0
votes
2answers
43 views
Is it incorrect to explain the direction of a coded vector quantity?
For example, let's say that in a linear physics problem, all the data are given to a certain direction, and coded positively for direction to the right.
So +5m/s would be a velocity of 5m/s to the ...
-4
votes
0answers
29 views
Physics question based on motion in one dimension [closed]
2 trains $A$ and $B$ are moving in same direction at same track with $B$ ahead of $A$ with speed $u$ and train $A$ with speed $v$ ($v>u$). The driver of $A$ sees $B$ and starts decelerating with ...
-1
votes
0answers
37 views
If Galileo had an electronic scale [closed]
If Galileo had an electronic scale, capable of absorbing the collision (without breaking) of 1 Kg sphere dropped from the top of Pisa tower what would had been the maximum measurement registered after ...
1
vote
1answer
67 views
6 Story Building Swaying, Normal?
Preface:
I'm currently sitting at my desk on a 5th floor in a South Florida office building, as I was earlier this morning when I felt the building sway slightly. It wasn't continuous and the ...
0
votes
1answer
79 views
Help finding Delta T for a known position displacement with known accel/decel, etc
I'm looking for an equation to find the time it will take for a position displacement to happen, given known $V_{max}$, a (known) constant acceleration, deceleration, jerk, and displacement... and an ...
1
vote
0answers
17 views
Correct terminology for combined kinematic and dynamic state
They 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 ...
-3
votes
0answers
31 views
Projectile Motion and hexagon [closed]
A projectile passes through four vertices of a regular hexagon of side "a". Find its horizontal range.
Now the problem is to find the horizontal range, and the time of flight. Can you please help?
6
votes
3answers
160 views
Intuitive meaning of factor 2 in formula of vertical throw max height $h=v^2/2g$
This is a question about a simple thing. The simplified expression for maximum height in vertical throw is $h=\frac{v^2}{2g}$ , could anyone explain intuitively (analogies are welcome) why there is a ...
3
votes
1answer
43 views
Galaxy Kinematic Fitting: How to deal with Point Spread Function (PSF)
The past few months I have been studying astronomy and Integral Field Spectroscopy (IFS). What I want to do is to fit a galaxy kinematic model to data (ie: estimate the model parameters that give the ...
-1
votes
1answer
35 views
Vectors and motion in a plane [closed]
A particle travels with speed $50 m/s$ from the point $(3,-7)$ in the
direction $7i-24j$ . Find its positional vector after 3 seconds.
My approach:
It has travelled a distance of 150m in the ...
1
vote
2answers
28 views
How to calculate pressure exerted on the wheels of a robotic car?
I need some help in designing my robotic car. So its going to have 4 wheels, each driven by a 12-volt motor. It occurs to me that the weight of the chassis itself will exert some pressure on the ...
-4
votes
2answers
59 views
Is it possible to calculate distance if non-constant acceleration is unknown? [closed]
I know that the distance travelled in non constant acceleration is $d=\int_a^b f(x)\mathrm{d}x$, but is it possible to calculate the distance without knowing the value of $f(x)$?
0
votes
1answer
56 views
Short-duration forces
In circular motion, it is said that the centripetal force acts only for a very very short period of time, hence is able to only change the direction but not magnitude of the velocity.
Similarly in a ...
0
votes
1answer
89 views
Relative Velocity problem
I was solving many problems on relative velocity and observed that when the question asks,
"what is the minimum time taken by the boat/man to cross the river.?"
so the solution says that he ...
-3
votes
0answers
24 views
Length Traveled from Complete Stop [closed]
A one-meter long rifle fires a bullet at a velocity of 800 m/s. What is the average acceleration experienced by the bullet when it is fired? (Hint: You need to find the time it takes the bullet to ...
-2
votes
0answers
39 views
Whats the theoretical max speed to go around the world? [closed]
I light of the new Scramjet tests I have a question thats been bogging me.
I live in Denmark, about the furthest i can travel is to New Zeeland which is roughly on the opposite side of the earth.
...
-1
votes
3answers
106 views
+50
Static friction force on a block in a tunnel
Linked to this Comparing Static Frictions
Suppose there is a cuboidal vertical tunnel , and a cubical block in it such that all surface of the block are in contact with the four walls of the ...
-1
votes
1answer
49 views
Projectile motion: Thrust in x direction = acceleration in x direction? [closed]
I understand that in projectile motion, when an object is solely under the influence of gravity, there is no acceleration in the $x$-direction (with the acceleration due to gravity in the $y$ ...
1
vote
2answers
73 views
Relation between the time, velocity and acceleration
This is question from I.E. Iredov's General Physics:
$1.22$ : The velocity of a particle moving in the positive direction of the $x-axis$ varies as $v = α \sqrt x$, where $α$ is a positive ...
7
votes
1answer
458 views
I reached a result concerning displacement with quantized time intervals. Am I on to something?
A few days ago, I realized a similarity between distance with constant acceleration, $d = v_i t + 1/2 a t^2$, and the sum of integers up to n, $(n^2 + n)/2$. This came up again today when I decided to ...
-4
votes
1answer
43 views
How to calculate average speed when time is greater than distance? [closed]
I understand that average speed is calculated as $\frac{distance}{time}$ however this question says the time is greater than speed. Here's the question:
A bicycle travels 15 Km (kilometers) in 30 ...
13
votes
1answer
206 views
Modelling the movement and jumps of a chalk while drawing a dashed line on a blackboard
You probably know that if you try to draw a line using a piece of chalk on a blackboard , under some conditions (for example, $\alpha<\frac{\pi}{2}$ in the picture below) you will have a dashed ...
6
votes
4answers
148 views
Integrating radial free fall in Newtonian gravity
I thought this would be a simple question, but I'm having trouble figuring it out. Not a homework assignment btw. I am a physics student and am just genuinely interested in physics problems involving ...
1
vote
3answers
163 views
What does it mean if a body has kinetic energy?
What does it mean if a body has kinetic energy?
Does it mean that the momentum vectors of each particle of that body has the same direction?
What about angular momentum?
1
vote
2answers
133 views
How can I solve for time without knowing the vertical velocity?
A guy posted this problem on a forum:
There is a bird sitting on a pole of height h. you throw a rock at it and the moment the rock leaves your hand the bird starts flying horizontally away from ...
0
votes
1answer
85 views
Reachable area of cannonball given fixed initial speed [closed]
The trajectory of a cannonball fired from the origin with initial speed $v_0$ at an angle $\theta$ is given by
$$y = x\tan\theta - \frac{g}{2v_0^2 \cos^2\theta}x^2.$$
For fixed $v_0$, at what angle ...
1
vote
2answers
58 views
Area under a displacement graph
If the area under an acceleration-time graph denotes velocity and the area under a velocity-time graph denotes displacement, what exactly does the area under a displacement-time graph denote?
0
votes
0answers
21 views
Functions of time [duplicate]
Following are the functions of time:
$s(t)$ = distance a particle travels from time $0$ to $t$
$v(t)$ = velocity of a particle at time $t$
$a(t)$ = acceleration of a particle at time $t$.
If we want ...
1
vote
3answers
141 views
Functions of Time
1) Is position a function of time only or also velocity? Likewise, is velocity a function of time only or also the position?
2) The following are functions of time:
$s(t)$ = distance a particle ...
-1
votes
1answer
95 views
Elevator acceleration and velocity equation [closed]
I have a small question about the velocity and the acceleration of elevators.
I am looking for equations which is for a constant velocity and acceleration ( for exemple some elevators didn't have a ...
0
votes
0answers
30 views
Defining collision point in 3D [closed]
I have a problem with finding collision point of two objects with given speed vectors in 3d. Eg:
...
3
votes
1answer
73 views
Rotational velocity of face-on spiral galaxies using spectroscopy
I am doing my first steps in spectroscopy (IFS actually) and how we can learn more about galaxies by using it. I came up with a simple question which, unfortunately, I can not answer:
How can we ...
8
votes
2answers
290 views
Is acceleration an average?
Background
I'm new to physics and math. I stopped studying both of them in high-school, and I wish I hadn't. I'm pursuing study in both topics for personal interest. Today, I'm learning about ...
1
vote
1answer
125 views
Utilizing maximum acceleration $a$ for displacement $d$ with initial velocity $v_0$ and final velocity $v_1$
Problem
My goal is to move an object from point a to b (displacement $d$) as fast as possible utilizing the maximum available acceleration $a_{max}$, taking into account the initial velocity $v_0$ ...
0
votes
2answers
129 views
Given Angle, Initial Velocity, and Acceleration due to Gravity, plot parabolic trajectory for every “x”?
Given any Angle -> 0-90
Given any Initial Velocity -> 1-100
Given Acceleration due to Gravity -> 9.8
Plot every x,y coordinate (the parabolic trajectory) with cartesian coordinates and screen pixels ...
0
votes
3answers
117 views
Solve for Initial Velocity of a projectile given Angle, Gravity, and Initial and Final positions?
I've found equations http://www.physicsclassroom.com/Class/1DKin/U1L6a.cfm for solving everything (and rearranged to solve everything) to do with projectile motion EXCEPT this, even though it should ...
0
votes
1answer
94 views
Kinematics with non constant acceleration
A particle experiences an acceleration described by
$$
a=kx^{-2}
$$
where x is the displacement from the origin and k is an arbitrary constant.
To what value does the velocity v of the particle ...
15
votes
5answers
282 views
Does the mass point move?
There is a question regarding basic physical understanding. Assume you have a mass point (or just a ball if you like) that is constrained on a line. You know that at $t=0$ its position is $0$, i.e., ...
-1
votes
5answers
193 views
Why is momentum conserved (or rather what makes an object carry on moving infinitely)?
I know this is an incredibly simple question, but I am trying to find a very simple explanation to this other than the simple logic that energy is conserved when two items impact and bounce off each ...
0
votes
0answers
44 views
Inelastic relativistic collision [closed]
I have to solve the following problem:
A particle of rest mass, $m_1$, and velocity $v_1$ collides with a stationary particle of mass $m_2$. Find the rest mass $m$ and velocity $v$ of the resultant ...
3
votes
2answers
109 views
Is a heavier skier faster? [duplicate]
Is it true that a heavier skier goes faster? If it is, why is that?
My intuition would be that the speed gained by a skier should be independent from its mass, since both its acceleration and the ...
3
votes
2answers
70 views
Sign of acceleration
I'm developing an application using accelerometer sensor. I'm not good at physics so forgive me if the question is trivial. If I have 3 values of acceleration: $x$, $y$, $z$, I find acceleration ...
4
votes
2answers
1k views
Help me get out of a speeding ticket
I was driving uphill from a complete stop for a distance of .4 miles estimated to take 1 minute in a navigation app. I was pulled over right after cresting the hill. The cop had me on radar going ...
0
votes
3answers
307 views
Deriving equations of motion using integration
Please refer to my school textbook pg48 (of the book, and not the pdf counter) here: http://ncertbooks.prashanthellina.com/class_11.Physics.PhysicsPartI/ch-3.pdf
My doubt is in this context: (right ...
0
votes
0answers
87 views
An unmarked police car passed by a speeding car [closed]
Hi I'm trying to solve the problem
An unmarked police car traveling at a constant speed of 95 km/h is passed by a speeder traveling at 140 km/h. Precisely, 1.00 s after the speeder passes, the ...
0
votes
1answer
51 views
Projectile's angle in midflight
For a missile travelling from (0,0) at angle $\theta$ (to the horizontal) and initial velocity $u$, the y (vertical) position at time t is given by
$s_{y} = u\sin (\theta) t - 0.5gt^{2}$
and the x ...
0
votes
1answer
78 views
Circular motion and centrifugal force
Assuming a race car drives around in a circle of radius r, center (0,0), linear velocity v, and ignoring centrifugal forces and friction I can calculate the position at any time, t.
Angular velocity
...
1
vote
2answers
240 views
Projectile Motion with Drag
The overall goal is to write a Mathematica program that will compute the launch angle that will yield the greatest range with using [RandomInt] function, but I was having trouble with the physics.
In ...
4
votes
2answers
113 views
Best shape to reduce the splash of a droplet?
Our coffee machine catches the last couple of droplets, after your cup is removed on a shape to reduce plash of the coffee droplets.
These shapes are placed inside the spill reservoir.
The shape ...
