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 ...
2
votes
1answer
13 views
Question on static friction
This is the question, and the answer is given as 2).
Now my basic doubt is, are they asking us the direction of the total contact force on the object by the floor? Or, are they asking the direction ...
0
votes
1answer
44 views
Mechanics question (a block on top of a block)
This question is very similar to this one here.
A block of mass $m_1$ is placed on another block of mass $m_2$ lying on a smooth horizontal surface.
The coefficient of friction (static and ...
14
votes
4answers
326 views
+50
Why do whips hurt so much?
What exactly is the mechanism that makes a whip deliver such a strong impact? Elasticity, torque, or pressure? Just hitting something with a plank doesn't deal nearly as much damage. What's the ...
0
votes
1answer
33 views
In Newtonian pressure, what type of function is force?
This is pressure in Newtonian mechanics:
$$P=\frac {dF}{dA}.$$
What does this mean?
(Doesn't it mean that force is a function of area?)
What type of function is force?
0
votes
2answers
359 views
From knowing just the change in kinetic energy, can we find the friction force and engine power?
I understand this topic well enough to get all the task done because they aren't very creative. But for my exam I think I should have this clear.
During the acceleration the force from the engine is ...
6
votes
2answers
117 views
Confusion with derivation of fictitious forces
I read the mathematical derivation of fictitious forces on Wikipedia and I'm having trouble understanding it. I went on a few other sites looking for a better derivation, but they're all basically the ...
1
vote
1answer
132 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
2answers
66 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 ...
3
votes
3answers
59 views
The force arrow for centripetal force points in the opposite direction of my calculation?
I need someone to clarify a conceptual problem I can't seem to surpass. Image there is a rollercoaster loop and a rollerbcoaster car enters the loop at high speed.
Once the car completes the full ...
1
vote
0answers
41 views
Calculation of magnetic force magnitude from a parmenant magnet
I was wondering how strong a magnet should be in order to be able to horizontally attract 0.2 Kg of pure iron at a distance of 0.3 M. Since I know nothing about magnets, I started looking for ...
5
votes
4answers
281 views
Do strong and weak interactions have classical force fields as their limits?
Electromagnetic interaction has classical electromagnetism as its classical limit. Is it possible to similarly describe strong and weak interactions classically?
0
votes
1answer
111 views
Tension in a massless string around a pulley
A pulley having some mass has a massless string around it,with two unequal masses at the end of the string .Sufficient friction is present between pulley and the string such that the string does not ...
-4
votes
0answers
29 views
Is Gravity a Push force? [duplicate]
I am not a Science graduate, so may be I have an unclear concept. but one thing keeps coming to my mind so I thought to discuss here with someone interested in Gravity.
Here I go: "I feel there is NO ...
1
vote
1answer
224 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. ...
-1
votes
1answer
152 views
Example in the book: A two-cart train [closed]
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. ...
3
votes
1answer
71 views
Why does this screwdriver roll in a curved trajectory?
I am trying my level best to give this screwdriver a horizontal 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 ...
0
votes
1answer
42 views
Calculate magnitude of force acting on some area by falling object
I have simple question: is it possible to calculate magnitude of force acting on some area by falling object?
Let's say I have an object with mass $5\text{ kg}$. I drop that object in height 1 ...
2
votes
1answer
102 views
Is any work done when I walk?
I am trying to figure out the amount of work done when I walk X miles or for X minutes. So I got Work=Force x Distance and Force=Mass x Acceleration and Acceleration=(change in velocity)/time. I am ...
-3
votes
0answers
31 views
Block over block Problem [closed]
There are two blocks one over the other , both on ground , masses are 2 kg for top one and 5 kg for bottom one , coefficient of friction between both is 0.8 and between lower one and ground is 0.2 . ...
0
votes
1answer
65 views
What type of pump to lift water up 10 metres? [closed]
I've looked at the following question but I'm not sure it answers my question (end): -
Calculating the mechanical power of a water pump
by Phil Frost
I am building a Koi carp pond at the ...
1
vote
1answer
111 views
Buoyancy Problem - Cubes in water
I have a tank with water (10 m high) , with an ideal seal at the bottom (water can't fall down, but can enter bodies).
I have a system of 6 cubes ( of polystyrene density= 20 Kg/m^3) with dimension ...
3
votes
1answer
105 views
Is there any potential associated with magnetism
Can anybody please tell me if magnetism is a conservative force or if there is a field associated with it? How to reason? One thing I know is that the work done by a magnetic force is $0$.
-4
votes
0answers
31 views
Basic force in gravity responsible for attracting everything including nonmetal [closed]
Why do things get attracted? It is said that there is a magnetic field around the earth, but how can the attraction of non-metals be explained in terms of magnetic fields?
How can one generate this ...
2
votes
2answers
70 views
Sum of all forces
Let us glue up these two images, where we get closed loop thrust of water. Force $F_3$ has direction $-x$ and force $F_2$ has $x$ direction. What is the sum of all forces? Can it be more than zero? ...
0
votes
4answers
79 views
How can acceleration $a$ be zero when applied force $F$ is non-zero?
An object is at rest and stays at rest, but an attached rope pulls with increasing force. What is the acceleration?
The correct solution is that acceleration is constant and 0. Obviously $a= dv/dt ...
1
vote
4answers
61 views
Action Reaction when I pushing a trolley?
I tried to explain how those force work but I can hardly figure it out.
I exerted a force on the trolley and there will be a force on trolley on me as well. This is the newton's third law. But why the ...
-4
votes
3answers
77 views
Safest place to sit in the car [closed]
I have to sit in a car which has normal seats in the front, and lounge type chairs at the back, with seatbelts only in the front. The driver drives fast, and I think I may have an accident. So, ...
-1
votes
3answers
146 views
How much torque does it take to turn a doorknob? [closed]
How much torque does it take to turn a doorknob? I'm not looking for an exact answer, just a ballpark for someone who doesn't have a sense of everyday amounts of torque.
Here's a very ordinary ...
5
votes
1answer
144 views
Magnetic force doesn't do work and therefore can't change the KE of a particle?
I am having a real hard time understanding the principles behind a question I've come across during test prep. Here is the question:
Q: A proton and an electron are traveling in the uniform ...
-4
votes
0answers
29 views
Find amount of force to move a 18 kg mass 0.1 seconds [closed]
Force is coming from two pistons pushing at 45 degrees applied to two adjacent corners of a square (0.6 m x 0.6 m) rigid plane. Mass of the plane is 18 kg. Piston stroke is 20 cm, piston bore is 40 ...
-2
votes
1answer
61 views
Measuring vibration and converting to force (N) [closed]
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
107 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 ...
2
votes
1answer
70 views
Understanding Kepler's problem
I wanted to know a few things about elliptical motion, that I do not understand so far.
Let's imagine that we have an attractive gravitational two body problem where both bodies carry out elliptical ...
1
vote
2answers
66 views
force applied not on the center of mass
when applying a force not on the center of mass of the body, the body will get both linear and angular mumentom (right?).
does the linear velocety from this force (that is applied not on the center of ...
4
votes
5answers
4k views
How does centrifugal force work?
I know what centrifugal force is, but how does it work? Why are things forced to the outside?
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 ...
24
votes
5answers
2k views
With Newton's third law, why are things capable of moving?
I've got a rather humiliating question considering newton's third law
"If an object A exterts a force on object B, then object B exerts an equal but opposite force on object A" -> $F_1=-F_2$
...
1
vote
1answer
43 views
Universe with ZERO Fundamental Forces
Warning: I am not a physicist so please excuse my naivety!
As you all know, physicists think that there exist four fundamental forces.
Would a universe with zero fundamental forces be possible, at ...
1
vote
1answer
69 views
A block, a string and Newton's third law
So this is a general force diagram of the system shown. My question is, according to the third law, if the block is exerting a force of magnitude mg on the thread in the down direction, then the ...
0
votes
3answers
82 views
How would you determine whether an object is at equilibrium? [closed]
How would you determine whether an object is at equilibrium or not?
What is the definition of equilibrium?
1
vote
1answer
472 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
38 views
Equilibrium and Torque [closed]
How does one calculate the forces that exert on a wooden board held by two trestles if one knows the weight of the board as well as the distance of both trestles?
2
votes
2answers
174 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"
...
0
votes
1answer
463 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 ...
13
votes
6answers
654 views
Why do we still need to think of gravity as a force?
Firstly I think shades of this question have appeared elsewhere (like here, or here). Hopefully mine is a slightly different take on it. If I'm just being thick please correct me.
We always hear ...
1
vote
1answer
42 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 ...
2
votes
1answer
47 views
Summing moments, where have I gone wrong?
Because I don't have enough rep to post images, the question is question 3 part iii) from here: http://www.mei.org.uk/files/papers/m209ju_jk32.pdf
The surface at the contact point B is rough. The ...
0
votes
4answers
163 views
How do you tell what forces do no work?
The total mass of the children and the toboggan is 66 kg. The force the parent exerts is 58 N (18 degrees above the horizontal). What 3 forces/ components do no work on the toboggan?
I said the ...
-1
votes
1answer
50 views
What is the minimum wrap around angles of belt, timing belt and chain? [closed]
I read a website which said the minimum wrap around angle for belt on pulley is 120 degrees, However, it doesn't say whether it is belt or timing belt. Also I want to find the minimum wrap around ...
-2
votes
1answer
61 views
Question on friction [closed]
Please look at the figure carefully. The question is written, and one has to match the two columns 1 and 2 given under "choices and explanation". Please tell me if I am really wrong, i.e. would you ...
