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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133 views

Why is the range of a projectile proportional to the square of the initial velocity?

I was watching the MIT lecture about projectile motion and the lecturer asked why $$D=\frac{(v_0)^2\sin(2\alpha)}{g}$$ Why is it $(V_0)^2$ not $V_0$? It is a hypothetical question i know that the ...
2
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4answers
1k views

Is there a formula that gives the position of an object depending on the time, but which doesn't allow the object to surpass the speed of light?

I have found these two formulas: $v = at + v_0$ $x = \frac{1}{2}at^2 + v_0t + x_0$ a is the acceleration v is the velocity x is the position t is the time $v_0$ is the initial velocity $x_0$ is ...
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1answer
56 views

Is this movement possible?

My friend and I were arguing over some random facebook shared video. On this video, one guy throws up a rotating stick then, while it rotates on air, he kicks through it. Is it even possible? Or is it ...
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0answers
39 views

Projectile Motion [closed]

I've spent some time pondering the answer to this equation, without any success. A cannon is arranged to fire projectiles, with initial speed $v_0$, directly up the face of a hill of elevation angle ...
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1answer
41 views

Kinematics and dynamics - what pattern do they portray?

The Equations which are derived for kinematics and dynamics are some patterns related to the body in motion. What is the demarcation in the pattern that kinematic equations and dynamic equations ...
-2
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1answer
80 views

Find the average speed and velocity of the object [closed]

An object travels 11 m north and then turns around and travels 25 m south. If the total time of travel is 52 s what is the average speed and velocity of the object. I used the formula I was told ...
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2answers
138 views

Do rotation matrices rotate about inertial or body angles? [closed]

I have Yaw, pitch, and roll angles in that order (Euler 321) to apply to a body reference frame in cartesian coordinate system. I want to know what the body reference frame vector coordinates are ...
-1
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1answer
96 views

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 [closed]

A particle is constrained to move around the unit circle in the xy plane according to (x,y,z) = (cos(t^2),sin(t^2),0) t >= 0 At what point should the particle be released to hit a target of (2,0,0)? ...
2
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1answer
197 views

Insight into Torricelli's Equation ($v^2=u^2+2as$) [closed]

Torricelli's Equation ($v^2=u^2+2as$) is usually presented as the particular formulation of the SUVAT system which doesn't involve t. It is derived from the others using some (perhaps well-motivated) ...
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3answers
150 views

Does circular motion cause centripetal force OR does centripetal force cause circular motion?

Does circular motion cause centripetal force, or does centripetal force cause circular motion, or are they both occurring hand in hand together instantaneously? One more question: If I project a body ...
-1
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2answers
67 views

Simple projectile motion question that I can't figure out [closed]

My initial choice was B, but apparently that should have been immediately eliminated. I simply found the root of the values squared. I know that horizontal motion would be constant velocity, and ...
0
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1answer
92 views

Linear Momentum Based Problem [closed]

A ball moving along a straight line collides elastically with another stationary ball of the same mass. At the moment of collision the angle between the straight line passing through the centres of ...
6
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5answers
10k 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 ...
-2
votes
1answer
23 views

Find X as a Function of Ampltiude [closed]

For a spring-mass system undergoing simple harmonic motion find the location(s) between -A and A where the spring potential energy is equal to the kinetic energy. You should find x as a function of ...
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3answers
91 views

Position, Velocity And acceleration relations

Today we showed our physics teacher our code for a basic physics engine. He told us that this code snippet is incorrect: ...
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2answers
77 views

What is happening when a jenga block tower wobbles?

Imagine I am 3/4's of the way through a Jenga wooden block game. I have a tower and it is starting to wobble. To me it seems there are two possible causes for this: the wood is compressing and ...
-1
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1answer
29 views

Initial Velocity and Brakes [closed]

the question is about Initial Velocity and Brakes. I have done the question which is attached and Iwas wondering if I did it corretly. If not, can you tell me where I have gone wrong or what I should ...
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0answers
24 views

Averaged energies in particle collisions

Let's have (in CM frame) process $x + y \to x + y + z$, where $x, y, z$ correspond to (in general) different particles with non-zero masses. The total energy of process is $E$. How to calculate ...
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2answers
164 views

Stellar outflows in the Milky Way

There appears to be a lot of evidence that gas flows outward in Galaxies. I've been trying to parse through the available data and am unable to get a clear answer to this question: is there any ...
2
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2answers
4k views

Why do far away objects appear to move slowly in comparison to nearby objects?

When we are in a moving train, nearby stationary objects appear to go backwards. In Physics, relative velocity can be employed to explain the phenomenon: velocity of object w.r.t train = velocity ...
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3answers
206 views

Why is the constant velocity model used in a projectile motion derivation?

I was re-studying university physics last week, I'm now in the chapter about kinematics in 2 dimensions and specifically the one treating projectile motion. In page 86 of his book (Serway - Physics ...
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2answers
675 views

Monkey and tree - projectile motion

The famous scenario: A hunter is trying to shoot a Monkey hanging from a tree. However, this question doesn't mention the monkey jumping down from the tree or trying to escape. (The hunter uses a ...
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5answers
3k views

How a spacecraft travelling near light speed avoid asteroids?

How would a spacecraft traveling near light speed avoid a (relatively dense group of) asteroids? Or suppose such spacecraft is designed, how would the physics work for steering it inside such a ...
15
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5answers
3k views

Zero velocity, zero acceleration?

In one dimension, the acceleration of a particle can be written as: $$a = \frac{dv}{dt} = \frac{dv}{dx} \frac{dx}{dt} = v \frac{dv}{dx}$$ Does this equation imply that if: $$v = 0$$ Then, ...
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2answers
762 views

Gas viscosity at high pressure, high temperature

EDIT 1 PER COMMENTS I am wanting to model nitrogen gas viscosity as a function of pressure and temperature OR learn of an existing equation that models nitrogen viscosity for the pressure and ...
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5answers
10k views

How can an object with zero acceleration move?

My physics text has a problem in which it is said that a person moves a block of wood in such a way so that the block moves at a constant velocity. The block, therefore, is in dynamic equilibrium and ...
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1answer
43 views

kinematics: parabolic movement [closed]

How does the formula $ax^2$ is affected by the angle and the power of the launch of, let's say, a cannon ball, (regardless of its mass)? I am trying to create a simulation, and everything I have to ...
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2answers
150 views

How does the object at constant speed pass the accelerating object?

A car starts from rest and move with constant acceleration of $4\frac{m}{s^2}$ and at the same time a motorcyclist moving with a constant speed of $36\frac{km}{hr}$ overtakes and passes the car. ...
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2answers
64 views

Finding equation for exponential deceleration

Let's say my ship's velocity during deceleration phase is given by: $$ v(t) = v_0 \exp(-k t) $$ where $v_0$ is the speed at the time of starting deceleration and $k$ is arbitrary constant. My ...
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3answers
429 views

How to find stopping distance of a car? [closed]

I am trying to calculate minimum stopping distance of a car once the brakes are applied. I know the velocity at braking instant, i also know the distance from the obstacle. I found out that $$ d = ...
0
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3answers
40 views

Time taken for a body to reach a velocity of sqrt(a) from 0 under an acceleration a? [closed]

Lets say body starts from rest and would like to attain a velocity of sqrt(a) , where a is the acceleration (constant) of the body. By laws of motion we get t = 1/sqrt(a) which in the case of a --> ...
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1answer
427 views

Can the equations of motion be used for both instantaneous and average quantities?

I have three equations of motion: $$v = u+ at , $$$$s = ut + \dfrac{1}{2} at^2 , $$$$ v^2 = u^2 + 2as.$$ Can I use them for both finding instantaneous and average quantities? Suppose I want to find ...
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3answers
144 views

My physics teacher gave us this equation $v= -3 +3t$

She asked us if the body was accelerating or slowing down, and I immediately said that it was accelerating (because the $a=3>0$). Then she said that I was wrong because the direction of the ...
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2answers
99 views

Uniformly Accelerated Motion question

A ballast bag is dropped from a balloon that is 300 m above the ground and rising at 13 m/s. For the bag, find the maximum height reached. Now the book gives me this answer - $V_i$ = initial ...
0
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1answer
59 views

vector and position and acceleration [closed]

I really need your help with two problems. Consider a moving object that can be described by the position function r(t) = [(8.00m/s )t-[( 4.50m/s^3 )t^3 ]î +(− 2.00 )t^2+10.0m]ĵ In unit­vector ...
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1answer
45 views

Need help with acceleration question? [closed]

I don't understand how to solve this question involving two constant accelerations.
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2answers
33 views

Kinetic energy on macro and micro situation

I just have this random question in my mind. If you drop something in deep space, and it falls due to a gravitational pull. As it's falling, its kinetic energy increases. I just wonder, is the average ...
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0answers
46 views

How velocity progresses over time with a non-constant acceleration? [closed]

A $0.25\text{ kg}$ sphere of radius equal to $0.07\text{ meters}$ is dropped from rest from the top of a building. Granted that it will not hit the ground before, when and after what distance ...
0
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1answer
97 views

Motion in the gravitational field along a trajectory [closed]

A point particle of mass $m$ is moving in the gravitational field along some trajectory which is described by the function $y=y(x)$, which is in a vertical plane and is continuous. Initial ...
0
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1answer
48 views

Can I use $(v_1+v_2)/2$ to find average velocity? [closed]

An object is traveling from a point $M$ to a point $N$ with a velocity $v_1 = 600 \,\rm km/hr$ and comes back with a velocity $v_2 = 400 \,\rm km/hr$. What is the average speed of the object? Can we ...
1
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1answer
44 views

Speed of a river [closed]

I've got a problem (Sorry if it's too basic). It is: Going upstream in a canoe, the passengers throw an empty bottle. They keep rowing for 60 minutes, and move 2 kilometers upstream. They then start ...
0
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1answer
53 views

Minimum Distance for “Speed of Light Approach”

I tried to calculate the minimum distance between a planet and a test mass for the mass to attain the speed of light on colliding with the planet's surface if it were released from rest at the initial ...
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1answer
45 views

Motion in 2 dimentions relating $\delta x$ to $\delta y$ [closed]

In a self exercise i was trying to solve this users question what is the initial velocity if angle and range is given? My aim is 1) not to use the standard equations of motion but rather calculus; ...
0
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1answer
37 views

Definition of a symbol $s_{NN}$ appearing in particle physics

What is the meaning of $s_{NN}$ in particle physics? See e.g. here http://www4.rcf.bnl.gov/brahms/WWW/thesis/karabowicz_phd_thesis.pdf page 18 in the pdf. What is its relation to energy? I ...
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1answer
56 views

a question regarding relative velocity

"Consider a gravity-free hall in which an experimenter of mass $50~\text{kg}$ is resting on a $5~\text{kg}$ pillow, $8~\text{ft}$ above the floor of the hall. He pushes the pillow down so that it ...
0
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2answers
107 views

What causes the random movement of particles inside a conductor?

I'm reading about currents in electricity right now, and it was mentioned that even if there's no electric field inside a conductor, charged particles inside are still undergoing random movement. I ...
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8answers
596 views

Can velocity be an undefined quantity?

We have the image below displaying the uniform velocity by time-distance graph. At every point velocity is constant but what if distance and time both become zero as at origin in the graph is? The ...
2
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1answer
373 views

Is rate of change of velocity wrt distance and rate of change of velocity wrt time the same thing?

Is rate of change of velocity wrt distance and rate of change of velocity wrt time the same thing?If both are same can we define acceleration in the former way? Please explain using calculus.
2
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1answer
73 views

How to find the function of acceleration respect to time while having the function of acceleration with respect to velocity

As everyone know that the integral of acceleration respect to time will give the function of velocity respect to time. However, my question concern the different case when the function of a(t) is not ...
0
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2answers
67 views

Height of building [closed]

How would I find the height of a building? I have been given the initial velocity, the angle at which the object was thrown, and the landing distance. And I was able to successfully compute the ...