All Questions
Tagged with motion or kinematics
489 questions with no upvoted or accepted answers
-1
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1
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35
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How can I change the angle in this equation to show the model?
I just can't understand how I can input different angles of launch into this equation to model the said angle. The example given is at 45 degrees but how can I change that to 30 degrees, for example?
...
-1
votes
1
answer
115
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Physical interpretation of complex numbers, part 2
I walk in the x direction, if I walk twice as fast, 2x, if I walk backwards, -x. What about ix? If I say that I walk an imaginary distance ix then this means in physics and maths that I walk ...
- 365
-1
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1
answer
230
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How does relative motion theory adjust other variables than kinematics' basics like velocity or displacement?
I have been confused on this concept for a while - suppose a boy is going from east towards west with some velocity on a bicycle and rain is falling in a vertical downwards direction.
Then, if we ...
-1
votes
2
answers
125
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Loss of simultaneity in special relativity
I was recently reading Introduction to Classical Mechanics by David Morin and while reading special relativity I came up with a paradox I am not able to resolve. It is basically related to the loss in ...
- 261
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1
answer
229
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Finding the drag force from the final velocity of a falling object
I know the velocities (v) of an object after it fell for respective distances (s). From that alone, is it possible to calculate the drag force at a specific moment in time? If not what else would I ...
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2
answers
5k
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What does speed of an object relative to water mean?
A swimmer swims with the velocity 1.25 m/s "relative to water". He has to swim across the river which is 150 meters wide. If his direction of velocity is perpendicular to the stream, he is taken away ...
- 203
-1
votes
3
answers
289
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The distance of an object undergoing constant acceleration
Is the distance an object moving increases with time if it is accelerated with a constant rate?
I mean, doesn't it depend on the direction the object is traveling? if I throw an object upward, wouldn'...
-1
votes
1
answer
31
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projectiles-kinematics
Let's just say that I have two identical spheres at the same height. Both of them are given the same push (same velocity). One of the spheres is projected vertically upward and the other is projected ...
-1
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1
answer
308
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Integration of Acceleration to Get Delta Velocity
How do you get delta velocity if you have times t1 and t2 and their velocities v1 and v2, but you only know their accelerations a1 and a2. If you integrate over accelerations a1 and a2, do you get a "...
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-1
votes
2
answers
7k
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Distance and Displacement from a velocity vs. time graph
My teacher is saying that the distance covered will be equal to the area of the trapezium in the graph, but the displacement will be equal to the area of the triangle (with purple hypotenuse). I ...
- 101
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2
answers
255
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If a bullet is shot up in the air off a cliff, will the final velocity be greater?
Since acceleration due to gravity is 9.80m/s^2 wouldn't the final velocity keep increasing by 9.80m/s each second that the bullet is in the air since velocity has a time dependence?
If that is the ...
- 19
-1
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2
answers
444
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Velocity gradient in fluids
I am mathematician and I am interested to know more about fluid mechanics. I need an explanation of the physical meaning of the derivative of velocity with respect to position.
- 9
-1
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2
answers
102
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Distance an object has fallen given time
I am in Honors Physics, and need help understanding this:
The acceleration of Earth's gravity is 9.8 $m/s^2$, so when an object starts from rest, 9.8 $= x/t^2$, where $x$ is distance the object will ...
- 101
-1
votes
2
answers
241
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How can you determine an object's displacement as a function of time in real life?
Image you have an object, say a projectile or a vehicle, moving with non-uniformly accelerated motion. If you were to measure its position in space say, every second or every tenth of a second, is it ...
-1
votes
1
answer
2k
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Why we take gravitational acceleration negative even if the body is moving in the direction of the gravity?
let we throw a ball vertically upward and it comes back to the ground after 6 seconds. So to calculate the initial velocity we use $s=ut+(1/2)gt^2$
but we take the value of $g$ negative for the whole ...
- 1
-1
votes
3
answers
105
views
Can't figure out which equation to integrate in order to get velocity on the $y$ axis
Known: V velocity, a = positive constant, $ y = ax^2 $
Left side: $y = {dVy \over dt} {dt \over dy} \\ \int ydy = \int dVy \\ {y^2 \over 2} = Vy$
Right side: $y = {dVy \over dt} {dt \over dx} \\ \int ...
- 19
-1
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1
answer
99
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Is the formula for average velocity a definition or derived quantiy?
I am preparing to take calculus-based physics. I have experience in algebra-based physics, in which the following formula was heavily emphasized:
$$v_{avg} = \frac{\Delta x}{\Delta t}$$
I assumed ...
- 964
-1
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1
answer
5k
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How to calculate accurate yaw using Magnetometer and Accelerometer
I'm currently using mobile device accelerometer+gyro+magnetometer attitude to get roll, pitch, and yaw. However, yaw is drifting and becoming not accurate over time.
I read there is a way to calculate ...
- 99
-1
votes
1
answer
155
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Why Net force is not zero and hence COM is not fixed
In a classical center of mass problem where a man is standing on a boat and then walks to another end we solve it by the fact that the COM is fixed or at rest as the net force is zero- forces are only ...
- 91
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1
answer
1k
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Finding kinematic equation with time-varying acceleration
I would like to obtain a relation between initial velocity and distance covered till velocity is zero, with time varying acceleration. For a constant acceleration we can solve:
\begin{align*}
\int_{0}^...
- 99
-1
votes
1
answer
475
views
Optimal release angle for rubber-band powered catapult
I'm building a rubber-band powered catapult, and wondering what the optimal release angle is (for maximum range). If velocity is held constant, it's obviously $\pi/4$, but with rubber bands, the ...
- 109
-1
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1
answer
399
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Derivative of horizontal range vs launch angle?
So my task was to shoot a marble at different angles with the same initial velocity at an elevation of $0.26$ meters to find the relationship between horizontal range and launch angle.
I was able to ...
- 19
-1
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2
answers
121
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Motion of blocks
I've been given the value of $F=mg/2$. And I need to find the acceleration of block 2. First I need to know why would the block 2 even move? It should be stationary according to me. I know I'm wrong I ...
- 174
-1
votes
1
answer
965
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Projectile exploding in two masses
I'm working on the following problem:
A projectile with a mass 𝑀 and a velocity $𝑣(𝑡=0)=0$ explodes into two pieces. The energy gain from the explosion is 𝐸. What is the ideal mass distribution ...
- 1,449
-1
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1
answer
107
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Time traveled assuming instant acceleration/decelaration
I am working on sort of a motion planning algorithm where I need to estimate the time it takes to travel along a certain path of points (straight lines between consecutive points, i.e I am assuming ...
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votes
2
answers
2k
views
Equation for Figuring out the Displacement for a Projectile at an Angle
I'm wondering if anybody can simply tell me if there is a simple formula to solve for displacement when you've been given the launch angle and initial velocity? See; http://is.gd/LpT1EA
To some, it ...
-1
votes
2
answers
193
views
Simulating a car in an intersection
I'm somewhat confused. I want to simulate in real-time an intersection where cars have to turn left, right or go straight. What I have are 2 way points: One at the beginning of the intersection on ...
-1
votes
2
answers
42
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Is this correct regarding velocity of train?
So many yellow T drawn are just different position of train at different instants.The person is standing still at all those instants at one place.
If a train is moving at 5m/s.
Then for me , can we ...
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5
answers
800
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Can the initial time be non-zero?
I am just slightly confused about how initial time is chosen in mechanics. I keep thinking I have understood it but some doubts come up later.
Basically when I derived the constant acceleration ...
- 537
-1
votes
2
answers
89
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For how long is an objects velocity it's instantaneous velocity at time $t$?
Basically I'm asking if an object's instantaneous velocity at time $t$ is $8m/s$ and its instantaneous velocity at time $t^+$ (idk latex, but basically the t + an infinitely small number) is $10m/s$, ...
-2
votes
2
answers
236
views
Acceleration perpendicular to constant velocity in special relativity
In newtonian mechanics, if a body is experiences an acceleration that is perpendicular to the direction of motion at all times, it moves in a circle and the magnitude of it's velocity does not change....
- 57
-2
votes
1
answer
49
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Speed of atoms being pushed away
It is said that it is impossible to calculate one-way speed of light.
I have doubts in my small theory and I would like someone to correct me because I lack in knowledge in physics, and I'm surely ...
-2
votes
2
answers
2k
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How do you derive $v_f^2 = 2ad + v_i^2$ from $v_f = v_i + at$ and $d = v_it + (a/2)t^2$?
I'm trying to use substitution to find the equation Vf^2 = 2ad + Vi^2 from Vf = Vi + at and d = Vit + a/2(t^2), but I get stuck understanding part of the math. I've attached a picture, and you can see ...
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votes
2
answers
1k
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What is closing speed?
what is closing speed? the only information google was able to give me, is that closing speed is when a car is approaching another car both at 30m/s the closing speed is 60m/s, so what exactly is ...
- 137
-2
votes
1
answer
54
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How to express in terms of spacetime intervals the average speed of one participant having moved between two suitable others
Given a flat region of spacetime as set $\mathcal S$ of events together with values of spacetime intervals (up to a common non-zero constant) for each pair of events,
$s^2 : \mathcal S \times \mathcal ...
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-3
votes
2
answers
267
views
What exactly is happening to acceleration when direction changes?
As direction changes i know that acceleration occurs but what exactly is happening to it, is it increasing acceleration, decreasing acceleration, constant acceleration, negative acceleration or ...
- 137
-3
votes
1
answer
53
views
A projectile with huge initial speed
in a projectile, if the value of initial speed is very large, 2000 m/sec for example, and the shooting angle is not equal to 0 degrees
why would the rules of the maximal height and range (maximal ...
- 1
-3
votes
2
answers
60
views
If x is the position, how and why is one sure that a is displacement and b is acceleration in the given equation? x=a+bt²
I don't understand why a and b have to be displacement and acceleration respectively. Is that because of kinematics fist equation v-u+at?
-4
votes
1
answer
83
views
What is the acceleration experienced by a person walking into a tree or pole?
Please go to this website and view videos of people walking into things. I would like to know what is the deceleration their head experiences from this.
I have done my research on this already. A ...