This tag is for the classical concept of forces, i.e. the quantities causing an acceleration of a body. It expands to the strong/electroweak force only insofar as they act comparable to ‘classical’ forces. Use [tag:particle-physics] for decay channels due to forces and [tag:newtonian-mechanics] or ...
5
votes
2answers
157 views
Relativistic equivalent of a spring-force?
Usually what helps me understand a concept better in physics is to write a simulation of it. I've got to the point where I'm competent in the basics of special relativity, but, I can't figure out how ...
3
votes
2answers
858 views
Strong force, where is the seperation?
In class I got given a diagram like this: (albeit without the Electrostatic force line)
However the teacher told us the nucleons are typically separated when the force is zero. So as the string ...
3
votes
2answers
471 views
Ski Jumper's vertical velocity after 246.5m record?
What would be the vertical velocity of this ski jumper (ski flyer), after he first touches down, after he breaks the record with a 246.5m jump? What g force would he experience as he slows down?
...
2
votes
2answers
66 views
Intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
2
votes
2answers
152 views
Cantilever Beam - Maximum Shear of the Beam
A cantilever beam $3\ \text{m}$ long is subjected to a moment of $10\ \text{kNm}$ at the free end. Find the maximum shear of the beam.
The answer is "There is no vertical load, shear is zero"
...
2
votes
1answer
68 views
Convert a 200mm linear stroke into 90 degrees motion
Can anyone help me Convert a 200 mm linear stroke into 90 degrees motion with as much mechanical advantage as possible or into two 90 degrees motions with as much mechanical advantage as possible?
...
2
votes
1answer
166 views
Additional accelerating force during take off of a rocket?
During the take off of a rocket, the exhaust produces some pressure below the rocket, which gives an additional force. How large is this force in comparison to the force produced directly by the ...
1
vote
1answer
48 views
Forces on a particle moving in a vertical circle
In the diagrma, a particle (A, mass 0.6kg) is moving in a vertical circle. The question is: When it gets to the lowest point, what is the tension in the light rod that is between the center of the ...
1
vote
1answer
35 views
Can Joule's First Law of Thermodynamics be Applied to Atomic Charges?
James Joule established that all forms of energy were basically the same and interchangeable. My question is if thas law is relevant in particle physics. Can a positive charge and a negative charge be ...
1
vote
1answer
113 views
Force and Torque Question on an isolated system
If there's a rigid rod in space, and you give some external force perpendicular to the rod at one of the ends for a short time, what happens?
Specifically:
What dependence does the moment of inertia ...
1
vote
1answer
442 views
Solving a Statically Indeterminate Truss with Energy Equations (Tricky)
Okay, first off, I know that there is a very similar problem about statically indeterminate trusses here, but my problem was a bit different and I didn't know how to adapt the answer for that problem ...
0
votes
1answer
91 views
Energy needed to lift and bring down an object
A mass of 0.5 Kg needs to be moved from point A to another point (B) which is 1 meters above point A. The time for this movement should be 0.2 seconds, then the mass is kept at position B for another ...
0
votes
1answer
49 views
Measuring vibration and converting to force (N)
The test is:
To have a rotating machine, bolted into a factory floor.
To measure the vibration on 3 axis (output of accelerometers can be acceleration or velocity in $\mathrm{m/s}$ or ...
0
votes
1answer
90 views
Shear Flow corresponding to Eccentric Shear Force of a Closed-section Beam (Structural Analysis - Mechanics)
Been stumped with this question for way too long... its a beam with a thin-walled rectangular cross-section, and a shear force is acting at a distance from the shear center. I know my decomposition of ...
0
votes
1answer
115 views
Opposing forces on an air cylinder
If an air cylinder is pushing two platens apart with a force of 100lbs, do the platens need to push back at 100lbs or 50lbs each to keep the cylinder from moving? Assume no friction and both platens ...
0
votes
1answer
204 views
What is the relation between fan blade and air flow CFM?
If I have a motor use in 2 cases, the 1st case I use standard blade and 20% longer blade in the 2nd case.
People told me that longer blade will create higher CFM. However, I am not totally sure. ...
0
votes
1answer
148 views
Force due to combination of free space and dielectric
I will make a generalized form of my question.
There are two point charges $q$, $x$ distance apart.
And there is a dielectric slab of thickness $t$ and of dielectric constant $K$.
Should the force ...
0
votes
1answer
160 views
Deceleration of Vehicle off pavement
How would I calculate the deceleration of a vehicle (ATV), wheels locked, on dirt? How long would it take to halt? How fast is it decelerating?
I used this calculator, but it seems incorrect for a ...
0
votes
1answer
448 views
Solving an indeterminate triangle truss structure (statics)
From the setup of two trusses as shown in this illustration, how can I solve for the axial reaction forces in the trusses, and in the points A and B (Ax, Ay, Bx, By)? It is assumed that the joints ...
-2
votes
1answer
125 views
Newton first law of motion, braking suddenly in car
While driving down the road, if you hit the brakes suddenly, your body moves forward. Explain the reason for this.
7
votes
0answers
284 views
Measurement of Tangential Momentum Accomodation?
(this question is a crosspost from theoretical physics.)
I am using atomic force microscopy (AFM) for characterizing
pores of the size of nanometers for application in gas flow. For
this, knowing ...
2
votes
0answers
46 views
Robot controling pouring process from a bottle
I need to solve a problem within mechanic of fluids for a part of my thesis. Robot will pick up a bottle of beer, cola, julebrus or any other kind of beverage. And then it has to bring it to the glass ...
2
votes
0answers
47 views
Semiflexible discrete polymer chain
Suppose we have a 2D polymer model described by a set of 2D vectors {$\mathbf{t}_i$} ($i=1,2,\dots N$) of length $a$.
The energy of the polymer is given by:
$$
...
2
votes
0answers
75 views
The force exerted by a ~10 Tesla magnet on a C13 isotope?
How much force would a ~10 Tesla magnet exert on a weakly magnetic C13 isotope? If I made a molecule of diamond with $N$ C13 atoms, how large would $N$ need to be for me to pull on it with something ...
2
votes
0answers
543 views
Forces and torques about the CENTER OF MASS of a physical pendulum
I'm currently stumped by the following situation. Say we've got a rectangular physical pendulum (think ruler with a hole-punch at one end).
It's trivial to analyze the motion of the pendulum with the ...
1
vote
0answers
37 views
Why the screwdriver roll?
I am trying my level best to give this screwdriver a vertical push only, but it is going in a circular path. I thought of uneven friction due to non-uniform normal reaction...what do you think? I have ...
1
vote
0answers
16 views
Acceleration by spherical particles (micron-scale) by an external force
I am looking for an expression for the velocity of a micron sized (1 - 10 micron diameter) sized particles under accelerating forces.
I have aerosols in mind.
This is what I have in mind
The ...
1
vote
0answers
42 views
effect of internal forces to a glider's descent
This is a continuation of a previous question, with more thinking applied, thanks to a helpful comment.
Imagine a glider is airborne in a breezeless sky. The glider is 3 KM high, is traveling at 100 ...
1
vote
0answers
38 views
Truck driven from a small motor that can carry a heavy load, yet can travel fast.
I am building a truck from trash as materials. I have one small motor and a a few small gears, but no other engineered materials are allowed. The truck must carry a load for a distance of 3m. The ...
1
vote
0answers
86 views
How much force is required to hold an umbrella?
Assuming a small umbrella (e.g. http://www.amazon.com/ShedRain-WindPro-Umbrella-Close-Size/dp/B001DL5WN0). What are the factors that need to be considered? I assume where I hold the umbrella might ...
1
vote
0answers
47 views
Fading transition and rotation of and object in 2D
I'm looking for sources about I guess dynamics subject.
The model I'd like to solve is reduced to a question of:
How does a force applied on a certain point of an object results in both fading ...
1
vote
0answers
79 views
What is the angle of the string with the vertical?
A heavy uniform sphere of radius $a$ has a light inextensible string
attached to a point on its surface. The other end of the string is
fixed to a point on a rough vertical wall. The sphere ...
1
vote
0answers
96 views
Hooke's Law and the shape of coils
I've learned in school that the force in a coil is $F=kx$, linear on how much the coil is stretched. Two questions:
Is it always linear for every shape of a coil? Does it remain linear if we ...
1
vote
0answers
148 views
Slackline Jump Tension
So a slackline is basically a bouncy tight rope.
I found a site that has a calculator for the tension of a static slackline
...
1
vote
0answers
308 views
FPS to MKS usage issues
I'm currently taking a high school physics class and we're doing friction problems now. I've been doing the ones that use MKS perfectly well, but when the problems start to use the FPS system, I'm ...
1
vote
0answers
369 views
What are the forces of constraint if there are multiple equivalent constraints?
Suppose a large (rigid) block is sitting on top of two smaller blocks of equal height $1$, both of which rest on the ground. We wish to find the position of the block (easy) and the forces of ...
0
votes
0answers
79 views
How to calculate mechanical advantage of a worm gear?
How to calculate mechanical advantage of a worm gear?
My textbook simply use the turn ratio as the mechanical advantage, but I'm not sure how that works.
My thinking: If the worm has a radius of ...
0
votes
0answers
133 views
Maximum Shear on a Beam - beam with fixed support on one end and hinge on other end
A beam $\displaystyle 3m$ long with fixed support on one end and hinge on the other end is subjected to a uniform load of $10\ kN/m$. What is the maximum shear of this beam?
The solution is this one:
...
0
votes
0answers
27 views
How do I minimize the the stress created by fore-aft forces?
My friends and I are designing a bench press spotter. Essentially, when the user needs help lifting the barbell due to muscle fatigue, an arm on each side of the user raises to provide assistance. ...
0
votes
0answers
62 views
On a Pilates reformer, how much resistance is from springs and how much from weight of user?
Here's picture of a Pilates Reformer machine: image
How much of the force required to move the carriage is based on the resistance of the springs, and how much is based on the weight of the user? ...
0
votes
0answers
213 views
How to calculate the force between two different magnets?
I'm doing an experiment and I need to calculate the force between two magnets with different stats, different sizes and flux density.
I learned physics in high school so I know all the terms.
In my ...
0
votes
0answers
50 views
Atomic force microscopy
I have these questions about force spectroscopy which I can't answer:
What is the basic principle of single molecule force spectroscopy and what is the main difference with chemical force microscopy? ...
0
votes
0answers
301 views
How to find Rotational and Translational Equilibrium of Hanging Masses on a Bar?
I am making a hanging mobile which needs to be done mathematically by calculating torque. The problem is, I can't seem to figure out how to solve for the distance of the two masses from the pivot ...
0
votes
0answers
107 views
How do I find the force on the charged sphere due to a dipole sitting inside?
I have a dipole sitting inside a charged sphere i.e. at the centre of the sphere. As far as I can see the force on the Dipole is zero because the external electric field on the dipole at $r=0$ is $0$. ...
0
votes
0answers
23 views
How is the shell placement in the transition zone of a staggered (double stack) magazine calculated assuming a reduction to single stack at the top?
High capacity pistol magazines are often designed to stagger, or double stack, rounds and transition the stagger into single file for feeding. How is the placement of rounds in the transition zone, ...
0
votes
0answers
57 views
Callculating the force on a metalic bar put in a coil
Lets consider a coil connected to a capacitor.
If the capacitor is loaded and then discharged trough the coil then that creates a magnetic field as shown here: ...
0
votes
0answers
84 views
Aerodynamic drag on a cannonball?
I'm trying to build a ballistics simulation where I shoot a cannonball. I want to allow for drag and am trying to work out the math to do so.
I can work the drag out using $F = Cd\times S\times ...
0
votes
0answers
97 views
Simple: What do these ballistic impact numbers represent?
I bought physics for game programmers, found here, today to study ballistic impact, but I'm confused as to where a few numbers are coming from. I'm basically looking to understand what the values ...
0
votes
0answers
133 views
Example in the book: A two-cart train
A two-cart train
The cars in Figure 5.6 are speeding up as they are pulled to the right with increasing speed across a frictionless surface. The ropes have negligible mass. We can concule that
A. ...
0
votes
0answers
82 views
Physics behind 2 different wall kicks
I'm looking at a situation where a sprinter starts at some distance x from a wall. The goal is to sprint to the wall, hit it, and get back to the start as quickly as possible. There are two ways ...
