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.

learn more… | top users | synonyms (2)

1
vote
0answers
53 views

Total cross section of particle decay

Suppose a particle A travelling along the $z$-axis and decays into particles B and C. The cross section is given by $$\frac{d\sigma}{d\cos\theta^*} = k(1+\cos\theta^*)^2$$ where $k$ is a constant ...
1
vote
1answer
161 views

How fast would one have to travel in an airplane in order to experience a continuous sunset?

For the sake of simplifying this problem and removing any guess work on how high the plane is flying, we'll say that our airplane is at 30,000 ft. as this is the average altitude for commercial ...
0
votes
0answers
53 views

Projectile motion with wind

I am trying to simulate a projectile motion with wind and gravity. (I'm a programmer so excuse my knowledge on the subject) I want to know launch rotation of a person in 3d to throw a ball forward ...
1
vote
1answer
138 views

Trajectory of a swimmer trying to reach the opposite bank [closed]

I came across the following question 2 days ago: $Q$. A swimmer is swimming in a river with a speed $u$ with respect to the speed of water which is $v$. It is assumed that the river has straight ...
0
votes
1answer
46 views

Kinetic Energy - use a log scale or not? [closed]

Lets say we have a series of balls and an eggs. All items have equal mass but are traveling at different velocities. Thus they have differing kinetic energies. Now, for each 'ball' object we have, ...
0
votes
1answer
229 views

Methods of solving relative motion questions using algebra or calculus

I am looking for algebraic methods (that may involve calculus) to solve problems of course needed for closest approach and shortest distance apart. I understand that geometric methods are often much ...
-1
votes
1answer
555 views

Can an object have 0 acceleration because its instantaneous velocity is 0? [duplicate]

If an object has an instantaneous velocity of zero, does this mean that its acceleration is zero?
2
votes
3answers
519 views

Basic question about acceleration [duplicate]

Very basic question. Please show where I'm wrong in the following reasoning. The movement of an object in function of time could be described as $$ x(t) = v t + x_{i} $$ if velocity is constant. If ...
-1
votes
2answers
51 views

Can I sum-up time?

If a kinetic process takes 1 second to complete(reach a point), and that process is repeated $n$ number of times, is this formula correct $t_t$=$n\times 1$ = total time in seconds? It's similar to a ...
1
vote
2answers
1k views

Why can velocity and acceleration be negative?

Why is speed and acceleration negative when $V_1$ of an object is say 150m/s, $V_2$ is 0 m/s and $\Delta d=0.50\,\rm m$? I found the time it takes which is 0.0033s and the acceleration to be 90909.09 ...
3
votes
1answer
327 views

Calculating Kryptonian speed in the movie “Man of Steel”

This is my first question, so I'm not sure if this is the right place to ask but: How would you go about calculating the speed of Kryptonians in the movie Man of Steel (2013)? Specifically, I'm ...
1
vote
1answer
99 views

How to explain this to my sir

We all know that $f = ma$. But for finding displacement, we always use: $$ s = s_0 + ut + \tfrac{1}{2} a t^2 $$ My sir, i don't know why for some reason uses this weird method: $$ F = ...
3
votes
1answer
70 views

Special relativity kinematics problem [closed]

I have this problem in SR kinematics. a spaceship travels near earth at c/2. it shoots off a light-ray at 45deg to its direction of travel (measured in its own ref frame). What is this angle in the ...
4
votes
2answers
555 views

Is Torricelli's law “wrong” for big holes? - Tank draining problem

Consider a tank full of water with a constant cross-sectional area A1 placed vertically on the ground. Now someone drills a hole of an area A2 in the bottom of the tank, and the liquid starts escaping ...
0
votes
0answers
52 views

One extra conservation equation or angle relation for a relativistic collision

Edit: It seems that the derivation for the center of momentum frame was incorrect, due to the fact that the center of momentum velocity changes after the collision. This is also true for the ...
0
votes
2answers
85 views

Best coordinate system for Projectile motion [closed]

What is the best coordinate system for describing the projectile motion? Rectangular coordinate system or n-t(normal and tangential) coordinate system.
-1
votes
2answers
78 views

Finding the initial velocity of projectile [closed]

What is the formula for calculating initial velocity of projectile using the conservation of energy given the mass, height, angle ?
-2
votes
1answer
42 views

Non zero accetion, varying speed [closed]

Can an object have non zero acceleration without having varying speed? How? Can you explain with an example please.?
0
votes
2answers
93 views

Derivation of $v=u+at$ [closed]

I read the derivation of $v=u+at$ using integration. The steps are as follows - $$\frac{dv}{dt}=a dt$$ $$dv=adt$$ $$\int dv=\int a dt$$ $$\int dv=a\int dt$$ $$v=at+c$$ My questions are as follows - ...
-4
votes
3answers
2k views

How to calculate meters per second speed when i have distance in meters and time in minutes [closed]

It might be a simple formula but I want to confirm it so can you please tell me how can I find speed in meters per second when I have Distance = 7720298 meters and total time 320941.03 minutes. How ...
0
votes
2answers
166 views

String wrapping around a motionless cylinder

A particle is connected to the end of a thin, weightless string, which has its other end connected to the cylinder, in such a way that motion of the particle causes the string to wrap around the ...
0
votes
2answers
121 views

Velocity and transfer of energy for a body in free fall

I just need to check if my understanding of the transfer of gravitational potential energy to kinetic energy is correct. Is anything wrong below? Say if a body were suspended at a height h above the ...
0
votes
2answers
531 views

Which point in the graph does a parachute open?

The diagram represents speed-time for a sky diver. He falls freely from an aircraft then opens a parachute and later lands safely on the ground. At which point did the parachute fully open? ...
2
votes
2answers
319 views

A car with constant speed doing a turn

Let's say we have a car with four wheels and the center of the car has a speed of 50km/h. There is no friction or air resistance. If the car is moving straight each wheel will also have a speed of ...
1
vote
1answer
61 views

Solve $a(t) = g - \beta v(t)$ for $t$

If $g$ is the acceleration due to gravity and $\beta$ is a known value, solve for the time $t$ it takes an object to reach a given velocity if the acceleration of the object is given by ...
-1
votes
1answer
28 views

Which acceleration equations? [closed]

Which equation gives the most accurate answer? $$a=g \sin⁡ α-μg \cos⁡ α\\ a=s/t/t\\ a=2s/t^2 -(2v_0)/t$$ Because i get three different answers. The scenario is a box sliding down on an inclined ...
1
vote
0answers
70 views

How Burmester's theory converts rotary motion of the crank to linear movement?

I have been studying the mechanism of Klann's Mechanical spider and there it was written that by Burmester's theory it converts rotary motion of the crank to linear movement. I tried searching but how ...
0
votes
1answer
87 views

Car wheels in a turn [duplicate]

I know that when a car is taking a turn, the front 2 wheels trace out 2 arcs having the same centre. I also know that the steering angle for the outside wheel is more than that of the inner wheel to ...
1
vote
0answers
69 views

Is shaking a phone enough energy to charge a smartphone?

Is shaking a phone enough energy to charge a smartphone? For example I'd like to use some kind of power generator to charge smartphone's battery but I'm wondering if shaking (by hand, or motion when ...
0
votes
0answers
15 views

Is there a “framerate” for the universe? [duplicate]

I've been wondering this for quite some time. I just can't wrap my head around the idea of truly continuous time. If time is truly infinitely divisible, then how can any object in the universe move? ...
0
votes
0answers
27 views

In Which Position A Co-passanger should Sit On A Turning Bike

Pardon me for this very basic mechanical science question. But I just want to clear my doubt it. Whenever I sit a behind someone on a bike I get confused when the the bike has to take a sharp turn. I ...
1
vote
4answers
2k views

Acceleration of a particle moving along a straight line

If a particle moves along a straight line, then can we say that the acceleration should be zero? and if not, then why? If the equation of the motion is linear, then the velocity is constant and if ...
4
votes
2answers
371 views

Question on particle decay process, conservation of energy

Why is $$\Sigma^0 \rightarrow \Lambda +\pi^0$$ not a possible process? Charge and baryon number both are conserved. There's no issue with strangeness that I can tell. The masses in $\frac{Mev}{c^2}$ ...
1
vote
1answer
120 views

Relativistic momentum of an electron

Suppose we have some interaction between a photon and an (initially) stationary electron, and we wished to find the final momentum of the electron. Should we solve this using conservation of momentum, ...
4
votes
4answers
475 views

Dodging paintballs

I was recently watching The Matrix, and was considering the speed at which one needs to move to literally dodge a projectile. Now, in real life, it is impossible to dodge bullets as such a feat would ...
0
votes
1answer
471 views

Force in a moving object that is not accelerating

If an object is traveling in a straight direction at a constant speed it has no acceleration, right? So if $F=ma$ and $a =0$ then force should equal 0. Does that mean a car traveling at a constant ...
0
votes
1answer
53 views

Question regarding the sail attached to a boat. [closed]

I came across a physics numerical in which the boat is travelling 45 degrees south-east. The direction of wind is towards north and the force that it exerts is constant force of 100 N on the sail. The ...
2
votes
4answers
703 views

What causes a car's velocity to follow the front wheels' direction?

I'm trying to simulate a car with correct physics models. In this example we let the car have a constant speed, and there are no forces (friction and drag) to slow down the speed. Here's a video that ...
0
votes
2answers
75 views

A car is moving in a circular trajectory with radius R=20m. The equation of motion is : x(t) = 15 + 8t – t^2 [closed]

We have to find the distance the car has traveled after 3s. Actually this question came up in an important exam, and the answer was: L=x(3)-x(0) But I think this is the answer for displacement, ...
1
vote
2answers
157 views

Time taken by a stone to reach the ground is independent of point of dropping

A balloon is rising. A stone is dropped and the stone takes $\frac{2u}{g}$ to reach ground (Nothing is known about $u$ and $g$ is the acceleration due to gravity), irrespective if the point of ...
1
vote
1answer
60 views

Angular and linear displacement of a turning car

My illustration is supposed to show a simplified car (with just two wheels, where the front wheel has been rotated $-90 \text{ degrees}$). Let the car travel at constant speed. This means that the ...
-1
votes
1answer
119 views

Question on Projectiles and momentum conservation [closed]

Firstly I apologize for bringing forth a high-school physics problem here, as some of you'll find this problem highly childish. But there are certain things i need to clarify about this. Q: An ...
1
vote
2answers
181 views

Computing distance traveled from jerk

When dealing with higher time derivatives like jerk, how does one find the distance traveled? Can it be calculated by just knowing time?
0
votes
0answers
26 views

Why does kinetic energy quadruple when speed doubles? [duplicate]

Why does kinetic energy quadruple when speed doubles? Please explain (in simple terms) with examples if possible.
0
votes
0answers
95 views

Drag coefficient of a rectangular prism

How do you find the drag coefficient, specifically for a rectangular prism-shaped body? What other factors must be taken into consideration when calculating this value?
1
vote
2answers
166 views

How to get these SUVAT formulae?

When learning kinematics, I have learned these three formulae $s=1/2(u+v)t$ $s=ut+1/2at^2$ $v^2=u^2+2as$ s = displacement u = initial velocity v = final velocity t = time a = acceleration My ...
0
votes
1answer
96 views

Why is parallel component of velocity along position vector considered rate of change of position?

If you have a position vector and a velocity vector of a particle, then the component of velocity vector along position vector is the rate of change of distance of the particle from the reference ...
-1
votes
1answer
50 views

Can anyone explain this formula graphically?

$$v^2=u^2+2as$$ v=final velocity; u=initial velocity, a=acceleration; s=displacement. I know and understand how this equation is derived.But, can anyone show me that $v^2=u^2+2as$ using graphic ...
1
vote
1answer
80 views

What is the meaning or purpose of inertial motions

It seems to me that, except for light, inertial motion is never possible in real world where there is gravity everywhere. It is at best some kind of idealization. But why inertial motions are so ...
2
votes
2answers
616 views

Submarine Speed Detection [closed]

A submarine can use sonar (sound traveling through water) to determine its distance from other objects. The time between the emission of a sound pulse (a “ping”) and the detection of its echo can be ...